commit 9df8ba7c63 upstream.
If probe fails after enabling the regulators regulator_put is called for
each supply without having them disabled before. This produces some
warnings like
WARNING: CPU: 0 PID: 90 at drivers/regulator/core.c:2044 _regulator_put.part.0+0x154/0x15c
[<c010f7a8>] (unwind_backtrace) from [<c010c544>] (show_stack+0x10/0x14)
[<c010c544>] (show_stack) from [<c012b640>] (__warn+0xd0/0xf4)
[<c012b640>] (__warn) from [<c012b9b4>] (warn_slowpath_fmt+0x64/0xc4)
[<c012b9b4>] (warn_slowpath_fmt) from [<c04c4064>] (_regulator_put.part.0+0x154/0x15c)
[<c04c4064>] (_regulator_put.part.0) from [<c04c4094>] (regulator_put+0x28/0x38)
[<c04c4094>] (regulator_put) from [<c04c40cc>] (regulator_bulk_free+0x28/0x38)
[<c04c40cc>] (regulator_bulk_free) from [<c0579b2c>] (release_nodes+0x1d0/0x22c)
[<c0579b2c>] (release_nodes) from [<c05756dc>] (really_probe+0x108/0x34c)
[<c05756dc>] (really_probe) from [<c0575aec>] (driver_probe_device+0xb8/0x16c)
[<c0575aec>] (driver_probe_device) from [<c0575d40>] (device_driver_attach+0x58/0x60)
[<c0575d40>] (device_driver_attach) from [<c0575da0>] (__driver_attach+0x58/0xcc)
[<c0575da0>] (__driver_attach) from [<c0573978>] (bus_for_each_dev+0x78/0xc0)
[<c0573978>] (bus_for_each_dev) from [<c0574b5c>] (bus_add_driver+0x188/0x1e0)
[<c0574b5c>] (bus_add_driver) from [<c05768b0>] (driver_register+0x74/0x108)
[<c05768b0>] (driver_register) from [<c061ab7c>] (i2c_register_driver+0x3c/0x88)
[<c061ab7c>] (i2c_register_driver) from [<c0102df8>] (do_one_initcall+0x58/0x250)
[<c0102df8>] (do_one_initcall) from [<c01a91bc>] (do_init_module+0x60/0x244)
[<c01a91bc>] (do_init_module) from [<c01ab5a4>] (load_module+0x2180/0x2540)
[<c01ab5a4>] (load_module) from [<c01abbd4>] (sys_finit_module+0xd0/0xe8)
[<c01abbd4>] (sys_finit_module) from [<c01011e0>] (__sys_trace_return+0x0/0x20)
Fixes: 3fd6e7d9a1 (ASoC: tas571x: New driver for TI TAS571x power amplifiers)
Signed-off-by: Philipp Puschmann <p.puschmann@pironex.de>
Link: https://lore.kernel.org/r/20200414112754.3365406-1-p.puschmann@pironex.de
Signed-off-by: Mark Brown <broonie@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
commit 0c824ec094 upstream.
For some reason, the MI2S DAIs do not have channels_min/max defined.
This means that snd_soc_dai_stream_valid() returns false,
i.e. the DAIs have neither valid playback nor capture stream.
It's quite surprising that this ever worked correctly,
but in 5.7-rc1 this is now failing badly: :)
Commit 0e9cf4c452 ("ASoC: pcm: check if cpu-dai supports a given stream")
introduced a check for snd_soc_dai_stream_valid() before calling
hw_params(), which means that the q6i2s_hw_params() function
was never called, eventually resulting in:
qcom-q6afe aprsvc:q6afe:4:4: no line is assigned
... even though "qcom,sd-lines" is set in the device tree.
Commit 9b5db05936 ("ASoC: soc-pcm: dpcm: Only allow playback/capture if supported")
now even avoids creating PCM devices if the stream is not supported,
which means that it is failing even earlier with e.g.:
Primary MI2S: ASoC: no backend playback stream
Avoid all that trouble by adding channels_min/max for the MI2S DAIs.
Fixes: 24c4cbcfac ("ASoC: qdsp6: q6afe: Add q6afe dai driver")
Signed-off-by: Stephan Gerhold <stephan@gerhold.net>
Reviewed-by: Srinivas Kandagatla <srinivas.kandagatla@linaro.org>
Cc: Srinivas Kandagatla <srinivas.kandagatla@linaro.org>
Link: https://lore.kernel.org/r/20200415150050.616392-1-stephan@gerhold.net
Signed-off-by: Mark Brown <broonie@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
commit 8ebf6da9db upstream.
Switching tracers include instruction patching. To prevent that a
instruction is patched while it's read the instruction patching is done
in stop_machine 'context'. This also means that any function called
during stop_machine must not be traced. Thus add 'notrace' to all
functions called within stop_machine.
Fixes: 1ec2772e0c ("s390/diag: add a statistic for diagnose calls")
Fixes: 38f2c691a4 ("s390: improve wait logic of stop_machine")
Fixes: 4ecf0a43e7 ("processor: get rid of cpu_relax_yield")
Signed-off-by: Philipp Rudo <prudo@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
commit b0d3869ce9 upstream.
... to protect the modification of mp->m_count done by it. Most of
the places that modify that thing also have namespace_lock held,
but not all of them can do so, so we really need mount_lock here.
Kudos to Piotr Krysiuk <piotras@gmail.com>, who'd spotted a related
bug in pivot_root(2) (fixed unnoticed in 5.3); search for other
similar turds has caught out this one.
Cc: stable@kernel.org
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
commit 28535877ac upstream.
It should use ad7797_attribute_group in ad7797_info,
according to commit ("iio:ad7793: Add support for the ad7796 and ad7797").
Scale is fixed for the ad7796 and not programmable, hence
should not have the scale_available attribute.
Fixes: fd1a8b9128 ("iio:ad7793: Add support for the ad7796 and ad7797")
Signed-off-by: YueHaibing <yuehaibing@huawei.com>
Reviewed-by: Lars-Peter Clausen <lars@metafoo.de>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
commit 69cf3978f3 upstream.
AFS keeps track of the epoch value from the rxrpc protocol to note (a) when
a fileserver appears to have restarted and (b) when different endpoints of
a fileserver do not appear to be associated with the same fileserver
(ie. all probes back from a fileserver from all of its interfaces should
carry the same epoch).
However, the AFS_SERVER_FL_HAVE_EPOCH flag that indicates that we've
received the server's epoch is never set, though it is used.
Fix this to set the flag when we first receive an epoch value from a probe
sent to the filesystem client from the fileserver.
Fixes: 3bf0fb6f33 ("afs: Probe multiple fileservers simultaneously")
Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
commit c4bfda16d1 upstream.
When an operation is meant to be done uninterruptibly (such as
FS.StoreData), we should not be allowing volume and server record checking
to be interrupted.
Fixes: d2ddc776a4 ("afs: Overhaul volume and server record caching and fileserver rotation")
Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
commit 12b94da411 upstream.
A DMA transfer can be in progress while vbus is lost due to a cable
disconnect. For endpoints that use DMA, this condition can lead to
peripheral hang. The patch ensures that endpoints are disabled before
the clocks are stopped to prevent this issue.
Fixes: a64ef71ddc ("usb: gadget: atmel_usba_udc: condition clocks to vbus state")
Signed-off-by: Cristian Birsan <cristian.birsan@microchip.com>
Signed-off-by: Felipe Balbi <balbi@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
commit 09b04abb70 upstream.
When building with Clang + -Wtautological-pointer-compare:
drivers/usb/gadget/udc/bdc/bdc_ep.c:543:28: warning: comparison of
address of 'req->queue' equal to a null pointer is always false
[-Wtautological-pointer-compare]
if (req == NULL || &req->queue == NULL || &req->usb_req == NULL)
~~~~~^~~~~ ~~~~
drivers/usb/gadget/udc/bdc/bdc_ep.c:543:51: warning: comparison of
address of 'req->usb_req' equal to a null pointer is always false
[-Wtautological-pointer-compare]
if (req == NULL || &req->queue == NULL || &req->usb_req == NULL)
~~~~~^~~~~~~ ~~~~
2 warnings generated.
As it notes, these statements will always evaluate to false so remove
them.
Fixes: efed421a94 ("usb: gadget: Add UDC driver for Broadcom USB3.0 device controller IP BDC")
Link: https://github.com/ClangBuiltLinux/linux/issues/749
Signed-off-by: Nathan Chancellor <natechancellor@gmail.com>
Signed-off-by: Felipe Balbi <balbi@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
commit 3d4b223868 upstream.
Since commit 7a04960560 ("kbuild: fix DT binding schema rule to detect
command line changes"), this rule is every time re-run even if you change
nothing.
cmd_dtc takes one additional parameter to pass to the -O option of dtc.
We need to pass 'yaml' to if_changed_rule. Otherwise, cmd-check invoked
from if_changed_rule is false positive.
Fixes: 7a04960560 ("kbuild: fix DT binding schema rule to detect command line changes")
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
commit d0550cd20e upstream.
The controller always supports link recovery for device in SS and SSP.
Remove the speed limit check. Also, when the device is in RESUME or
RESET state, it means the controller received the resume/reset request.
The driver must send the link recovery to acknowledge the request. They
are valid states for the driver to send link recovery.
Fixes: 72246da40f ("usb: Introduce DesignWare USB3 DRD Driver")
Fixes: ee5cd41c91 ("usb: dwc3: Update speed checks for SuperSpeedPlus")
Signed-off-by: Thinh Nguyen <thinhn@synopsys.com>
Signed-off-by: Felipe Balbi <balbi@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
commit ab6f762f0f upstream.
printk_deferred(), similarly to printk_safe/printk_nmi, does not
immediately attempt to print a new message on the consoles, avoiding
calls into non-reentrant kernel paths, e.g. scheduler or timekeeping,
which potentially can deadlock the system.
Those printk() flavors, instead, rely on per-CPU flush irq_work to print
messages from safer contexts. For same reasons (recursive scheduler or
timekeeping calls) printk() uses per-CPU irq_work in order to wake up
user space syslog/kmsg readers.
However, only printk_safe/printk_nmi do make sure that per-CPU areas
have been initialised and that it's safe to modify per-CPU irq_work.
This means that, for instance, should printk_deferred() be invoked "too
early", that is before per-CPU areas are initialised, printk_deferred()
will perform illegal per-CPU access.
Lech Perczak [0] reports that after commit 1b710b1b10 ("char/random:
silence a lockdep splat with printk()") user-space syslog/kmsg readers
are not able to read new kernel messages.
The reason is printk_deferred() being called too early (as was pointed
out by Petr and John).
Fix printk_deferred() and do not queue per-CPU irq_work before per-CPU
areas are initialized.
Link: https://lore.kernel.org/lkml/aa0732c6-5c4e-8a8b-a1c1-75ebe3dca05b@camlintechnologies.com/
Reported-by: Lech Perczak <l.perczak@camlintechnologies.com>
Signed-off-by: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
Tested-by: Jann Horn <jannh@google.com>
Reviewed-by: Petr Mladek <pmladek@suse.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Theodore Ts'o <tytso@mit.edu>
Cc: John Ogness <john.ogness@linutronix.de>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
commit 316ec15481 upstream.
A page table upgrade in a kernel section that uses secondary address
mode will mess up the kernel instructions as follows:
Consider the following scenario: two threads are sharing memory.
On CPU1 thread 1 does e.g. strnlen_user(). That gets to
old_fs = enable_sacf_uaccess();
len = strnlen_user_srst(src, size);
and
" la %2,0(%1)\n"
" la %3,0(%0,%1)\n"
" slgr %0,%0\n"
" sacf 256\n"
"0: srst %3,%2\n"
in strnlen_user_srst(). At that point we are in secondary space mode,
control register 1 points to kernel page table and instruction fetching
happens via c1, rather than usual c13. Interrupts are not disabled, for
obvious reasons.
On CPU2 thread 2 does MAP_FIXED mmap(), forcing the upgrade of page table
from 3-level to e.g. 4-level one. We'd allocated new top-level table,
set it up and now we hit this:
notify = 1;
spin_unlock_bh(&mm->page_table_lock);
}
if (notify)
on_each_cpu(__crst_table_upgrade, mm, 0);
OK, we need to actually change over to use of new page table and we
need that to happen in all threads that are currently running. Which
happens to include the thread 1. IPI is delivered and we have
static void __crst_table_upgrade(void *arg)
{
struct mm_struct *mm = arg;
if (current->active_mm == mm)
set_user_asce(mm);
__tlb_flush_local();
}
run on CPU1. That does
static inline void set_user_asce(struct mm_struct *mm)
{
S390_lowcore.user_asce = mm->context.asce;
OK, user page table address updated...
__ctl_load(S390_lowcore.user_asce, 1, 1);
... and control register 1 set to it.
clear_cpu_flag(CIF_ASCE_PRIMARY);
}
IPI is run in home space mode, so it's fine - insns are fetched
using c13, which always points to kernel page table. But as soon
as we return from the interrupt, previous PSW is restored, putting
CPU1 back into secondary space mode, at which point we no longer
get the kernel instructions from the kernel mapping.
The fix is to only fixup the control registers that are currently in use
for user processes during the page table update. We must also disable
interrupts in enable_sacf_uaccess to synchronize the cr and
thread.mm_segment updates against the on_each-cpu.
Fixes: 0aaba41b58 ("s390: remove all code using the access register mode")
Cc: stable@vger.kernel.org # 4.15+
Reported-by: Al Viro <viro@zeniv.linux.org.uk>
Reviewed-by: Gerald Schaefer <gerald.schaefer@de.ibm.com>
References: CVE-2020-11884
Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
commit 556d687a4c upstream.
In order to use compat_* type defininitions in device drivers
outside of CONFIG_COMPAT, move the inclusion of asm-generic/compat.h
ahead of the #ifdef.
All other architectures already do this.
Acked-by: Will Deacon <will@kernel.org>
Reviewed-by: Ben Hutchings <ben.hutchings@codethink.co.uk>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Cc: Naresh Kamboju <naresh.kamboju@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
commit 61da50b76b upstream.
Currently you can enable PPC_KUAP_DEBUG when PPC_KUAP is disabled,
even though the former has not effect without the latter.
Fix it so that PPC_KUAP_DEBUG can only be enabled when PPC_KUAP is
enabled, not when the platform could support KUAP (PPC_HAVE_KUAP).
Fixes: 890274c2dc ("powerpc/64s: Implement KUAP for Radix MMU")
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20200301111738.22497-1-mpe@ellerman.id.au
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
commit 8f97250c21 upstream.
The default control endpoint ep0 can return a STALL indicating the
device does not support the control transfer requests. This is called
a protocol stall and does not halt the endpoint.
xHC behaves a bit different. Its internal endpoint state will always
be halted on any stall, even if the device side of the endpiont is not
halted. So we do need to issue the reset endpoint command to clear the
xHC host intenal endpoint halt state, but should not request the HS hub
to clear the TT buffer unless device side of endpoint is halted.
Clearing the hub TT buffer at protocol stall caused ep0 to become
unresponsive for some FS/LS devices behind HS hubs, and class drivers
failed to set the interface due to timeout:
usb 1-2.1: 1:1: usb_set_interface failed (-110)
Fixes: ef513be0a9 ("usb: xhci: Add Clear_TT_Buffer")
Cc: <stable@vger.kernel.org> # v5.3
Signed-off-by: Mathias Nyman <mathias.nyman@linux.intel.com>
Link: https://lore.kernel.org/r/20200421140822.28233-4-mathias.nyman@linux.intel.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
commit 93ceaa808e upstream.
If a class driver cancels its only URB then the endpoint ring buffer will
appear empty to the xhci driver. xHC hardware may still process cached
TRBs, and complete with a STALL, halting the endpoint.
This halted endpoint was not handled correctly by xhci driver as events on
empty rings were all assumed to be spurious events.
xhci driver refused to restart the ring with EP_HALTED flag set, so class
driver was never informed the endpoint halted even if it queued new URBs.
The host side of the endpoint needs to be reset, and dequeue pointer should
be moved in order to clear the cached TRBs and resetart the endpoint.
Small adjustments in finding the new dequeue pointer are needed to support
the case of stall on an empty ring and unknown current TD.
Cc: <stable@vger.kernel.org>
cc: Jeremy Compostella <jeremy.compostella@intel.com>
Signed-off-by: Mathias Nyman <mathias.nyman@linux.intel.com>
Link: https://lore.kernel.org/r/20200421140822.28233-2-mathias.nyman@linux.intel.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
commit 1c2e54fbf1 upstream.
For userspace functions using OS Descriptors, if a function also supplies
Extended Property descriptors currently the counts and lengths stored in
the ms_os_descs_ext_prop_{count,name_len,data_len} variables are not
getting reset to 0 during an unbind or when the epfiles are closed. If
the same function is re-bound and the descriptors are re-written, this
results in those count/length variables to monotonically increase
causing the VLA allocation in _ffs_func_bind() to grow larger and larger
at each bind/unbind cycle and eventually fail to allocate.
Fix this by clearing the ms_os_descs_ext_prop count & lengths to 0 in
ffs_data_reset().
Fixes: f0175ab519 ("usb: gadget: f_fs: OS descriptors support")
Cc: stable@vger.kernel.org
Signed-off-by: Udipto Goswami <ugoswami@codeaurora.org>
Signed-off-by: Sriharsha Allenki <sallenki@codeaurora.org>
Reviewed-by: Manu Gautam <mgautam@codeaurora.org>
Link: https://lore.kernel.org/r/20200402044521.9312-1-sallenki@codeaurora.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
commit 49e0590e3a upstream.
A request may not be completed because not all the TRBs are prepared for
it. This happens when we run out of available TRBs. When some TRBs are
completed, the driver needs to prepare the rest of the TRBs for the
request. The check dwc3_gadget_ep_request_completed() shouldn't be
checking the amount of data received but rather the number of pending
TRBs. Revise this request completion check.
Cc: stable@vger.kernel.org
Fixes: e0c42ce590 ("usb: dwc3: gadget: simplify IOC handling")
Signed-off-by: Thinh Nguyen <thinhn@synopsys.com>
Signed-off-by: Felipe Balbi <balbi@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
commit 3c2760b78f upstream.
pci_driver.sriov_configure should return negative value on error and
number of enabled VFs on success. But now the driver returns 0 on
success. The sriov configure still works but will cause a warning
message:
XX VFs requested; only 0 enabled
This patch changes the return value accordingly.
Cc: stable@vger.kernel.org
Signed-off-by: Xu Yilun <yilun.xu@intel.com>
Signed-off-by: Wu Hao <hao.wu@intel.com>
Signed-off-by: Moritz Fischer <mdf@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
commit 0b59f10b1d upstream.
The problem is that the group key was saved as VNT_KEY_DEFAULTKEY
was over written by the VNT_KEY_GROUP_ADDRESS index.
mac80211 could not clear the mac_addr in the default key.
The VNT_KEY_DEFAULTKEY is not necesscary so remove it and set as
VNT_KEY_GROUP_ADDRESS.
mac80211 can clear any key using vnt_mac_disable_keyentry.
Fixes: f9ef05ce13 ("staging: vt6656: Fix pairwise key for non station modes")
Cc: stable <stable@vger.kernel.org>
Signed-off-by: Malcolm Priestley <tvboxspy@gmail.com>
Link: https://lore.kernel.org/r/da2f7e7f-1658-1320-6eee-0f55770ca391@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
commit 9a98e7a80f upstream.
Even if the actual screen size is bounded in vc_do_resize(), the unicode
buffer is still a little more than twice the size of the glyph buffer
and may exceed MAX_ORDER down the kmalloc() path. This can be triggered
from user space.
Since there is no point having a physically contiguous buffer here,
let's avoid the above issue as well as reducing pressure on high order
allocations by using vmalloc() instead.
Signed-off-by: Nicolas Pitre <nico@fluxnic.net>
Cc: <stable@vger.kernel.org>
Acked-by: Sam Ravnborg <sam@ravnborg.org>
Link: https://lore.kernel.org/r/nycvar.YSQ.7.76.2003282214210.2671@knanqh.ubzr
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
commit 2717769e20 upstream.
The code in vc_do_resize() bounds the memory allocation size to avoid
exceeding MAX_ORDER down the kzalloc() call chain and generating a
runtime warning triggerable from user space. However, not only is it
unwise to use a literal value here, but MAX_ORDER may also be
configurable based on CONFIG_FORCE_MAX_ZONEORDER.
Let's use KMALLOC_MAX_SIZE instead.
Note that prior commit bb1107f7c6 ("mm, slab: make sure that
KMALLOC_MAX_SIZE will fit into MAX_ORDER") the KMALLOC_MAX_SIZE value
could not be relied upon.
Signed-off-by: Nicolas Pitre <nico@fluxnic.net>
Cc: <stable@vger.kernel.org> # v4.10+
Link: https://lore.kernel.org/r/nycvar.YSQ.7.76.2003281702410.2671@knanqh.ubzr
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
commit 332e0e17ad upstream.
comedi_open() invokes comedi_dev_get_from_minor(), which returns a
reference of the COMEDI device to "dev" with increased refcount.
When comedi_open() returns, "dev" becomes invalid, so the refcount
should be decreased to keep refcount balanced.
The reference counting issue happens in one exception handling path of
comedi_open(). When "cfp" allocation is failed, the refcnt increased by
comedi_dev_get_from_minor() is not decreased, causing a refcnt leak.
Fix this issue by calling comedi_dev_put() on this error path when "cfp"
allocation is failed.
Fixes: 20f083c075 ("staging: comedi: prepare support for per-file read and write subdevices")
Signed-off-by: Xiyu Yang <xiyuyang19@fudan.edu.cn>
Cc: stable <stable@vger.kernel.org>
Signed-off-by: Xin Tan <tanxin.ctf@gmail.com>
Signed-off-by: Ian Abbott <abbotti@mev.co.uk>
Link: https://lore.kernel.org/r/1587361459-83622-1-git-send-email-xiyuyang19@fudan.edu.cn
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
commit ed87d33ddb upstream.
The DT2815 analog output command is 16 bits wide, consisting of the
12-bit sample value in bits 15 to 4, the channel number in bits 3 to 1,
and a voltage or current selector in bit 0. Both bytes of the 16-bit
command need to be written in turn to a single 8-bit data register.
However, the driver currently only writes the low 8-bits. It is broken
and appears to have always been broken.
Electronic copies of the DT2815 User's Manual seem impossible to find
online, but looking at the source code, a best guess for the sequence
the driver intended to use to write the analog output command is as
follows:
1. Wait for the status register to read 0x00.
2. Write the low byte of the command to the data register.
3. Wait for the status register to read 0x80.
4. Write the high byte of the command to the data register.
Step 4 is missing from the driver. Add step 4 to (hopefully) fix the
driver.
Also add a "FIXME" comment about setting bit 0 of the low byte of the
command. Supposedly, it is used to choose between voltage output and
current output, but the current driver always sets it to 1.
Signed-off-by: Ian Abbott <abbotti@mev.co.uk>
Cc: stable <stable@vger.kernel.org>
Link: https://lore.kernel.org/r/20200406142015.126982-1-abbotti@mev.co.uk
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
