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drm/amd/display: Add retry to read ddc_clock pin

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[ Upstream commit bd4905a958 ]

[WHY]
On customer board, there is one pluse (1v , < 1ms) on
DDC_CLK pin when plug / unplug DP cable. Driver will read
it and config DP to HDMI/DVI dongle.

[HOW]
If there is a real dongle, DDC_CLK should be always pull high.
Try to read again to recovery this special case. Retry times = 3.
Need additional 3ms to detect DP passive dongle(3 failures)

Signed-off-by: Paul Hsieh <paul.hsieh@amd.com>
Reviewed-by: Eric Yang <eric.yang2@amd.com>
Acked-by: Leo Li <sunpeng.li@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
This commit is contained in:
Paul Hsieh
2018-11-22 18:43:45 +08:00
committed by Greg Kroah-Hartman
parent a756020008
commit 1baca23ade
1 changed files with 17 additions and 6 deletions
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23
drivers/gpu/drm/amd/display/dc/core/dc_link.c
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@@ -324,7 +324,7 @@ bool dc_link_is_dp_sink_present(struct dc_link *link)
{
enum gpio_result gpio_result;
uint32_t clock_pin = 0;
uint8_t retry = 0;
struct ddc *ddc;
enum connector_id connector_id =
@@ -353,11 +353,22 @@ bool dc_link_is_dp_sink_present(struct dc_link *link)
return present;
}
/* Read GPIO: DP sink is present if both clock and data pins are zero */
/* [anaumov] in DAL2, there was no check for GPIO failure */
gpio_result = dal_gpio_get_value(ddc->pin_clock, &clock_pin);
ASSERT(gpio_result == GPIO_RESULT_OK);
/*
* Read GPIO: DP sink is present if both clock and data pins are zero
*
* [W/A] plug-unplug DP cable, sometimes customer board has
* one short pulse on clk_pin(1V, < 1ms). DP will be config to HDMI/DVI
* then monitor can't br light up. Add retry 3 times
* But in real passive dongle, it need additional 3ms to detect
*/
do {
gpio_result = dal_gpio_get_value(ddc->pin_clock, &clock_pin);
ASSERT(gpio_result == GPIO_RESULT_OK);
if (clock_pin)
udelay(1000);
else
break;
} while (retry++ < 3);
present = (gpio_result == GPIO_RESULT_OK) && !clock_pin;