mirror of
https://github.com/hardkernel/linux.git
synced 2026-06-03 01:36:52 +09:00
09d9e4d041
The Host Performance Buffer feature allows UFS read commands to carry the physical media addresses along with the LBAs, thus allowing less internal L2P-table switches in the device. HPB1.0 allowed a single LBA, while HPB2.0 increases this capacity up to 255 blocks. Carrying more than a single record, the read operation is no longer purely of type "read" but a "hybrid" command: Writing the physical address to the device in one operation and reading back the required payload in another. The JEDEC HPB spec defines two commands for this operation: HPB-WRITE-BUFFER (0x2) to write the physical addresses to device, and HPB-READ to read the payload. With the current HPB design the UFS driver has no alternative but to divide the READ request into 2 separate commands: HPB-WRITE-BUFFER and HPB-READ. This causes a great deal of aggravation to the block layer guys who demanded that we completely revert the entire HPB driver regardless of the huge amount of corporate effort already invested in it. As a compromise, remove only the pieces that implement the 2.0 specification. This is done as a matter of urgency for the final 5.15 release. Link: https://lore.kernel.org/r/20211030062301.248-1-avri.altman@wdc.com Tested-by: Avri Altman <avri.altman@wdc.com> Tested-by: Bean Huo <beanhuo@micron.com> Reviewed-by: Bart Van Assche <bvanassche@acm.org> Reviewed-by: Bean Huo <beanhuo@micron.com> Co-developed-by: James Bottomley <James.Bottomley@HansenPartnership.com> Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com> Signed-off-by: Avri Altman <avri.altman@wdc.com> Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.