Re: [PATCH v2] drm/amd/display: Force link_rate as LINK_RATE_RBR2 for 2018 15" Apple Retina panels

[Alex Deucher]

Applied.  Thanks!

Alex

On Sat, Jan 29, 2022 at 12:50 AM Aditya Garg  wrote:
>
> From: Aun-Ali Zaidi 
>
> The eDP link rate reported by the DP_MAX_LINK_RATE dpcd register (0xa) is
> contradictory to the highest rate supported reported by
> EDID (0xc = LINK_RATE_RBR2). The effects of this compounded with commit
> '4a8ca46bae8a ("drm/amd/display: Default max bpc to 16 for eDP")' results
> in no display modes being found and a dark panel.
>
> For now, simply force the maximum supported link rate for the eDP attached
> 2018 15" Apple Retina panels.
>
> Additionally, we must also check the firmware revision since the device ID
> reported by the DPCD is identical to that of the more capable 16,1,
> incorrectly quirking it. We also use said firmware check to quirk the
> refreshed 15,1 models with Vega graphics as they use a slightly newer
> firmware version.
>
> Tested-by: Aun-Ali Zaidi 
> Reviewed-by: Harry Wentland 
> Signed-off-by: Aun-Ali Zaidi 
> Signed-off-by: Aditya Garg 
> ---
> v2 :- Use C styled comments
>  .../gpu/drm/amd/display/dc/core/dc_link_dp.c  | 20 +++
>  1 file changed, 20 insertions(+)
>
> diff --git a/drivers/gpu/drm/amd/display/dc/core/dc_link_dp.c 
> b/drivers/gpu/drm/amd/display/dc/core/dc_link_dp.c
> index 05e216524..086f7ee2c 100644
> --- a/drivers/gpu/drm/amd/display/dc/core/dc_link_dp.c
> +++ b/drivers/gpu/drm/amd/display/dc/core/dc_link_dp.c
> @@ -5597,6 +5597,26 @@ static bool retrieve_link_cap(struct dc_link *link)
> dp_hw_fw_revision.ieee_fw_rev,
> sizeof(dp_hw_fw_revision.ieee_fw_rev));
>
> +   /* Quirk for Apple MBP 2018 15" Retina panels: wrong DP_MAX_LINK_RATE 
> */
> +   {
> +   uint8_t str_mbp_2018[] = { 101, 68, 21, 103, 98, 97 };
> +   uint8_t fwrev_mbp_2018[] = { 7, 4 };
> +   uint8_t fwrev_mbp_2018_vega[] = { 8, 4 };
> +
> +   /* We also check for the firmware revision as 16,1 models 
> have an
> +* identical device id and are incorrectly quirked otherwise.
> +*/
> +   if ((link->dpcd_caps.sink_dev_id == 0x0010fa) &&
> +   !memcmp(link->dpcd_caps.sink_dev_id_str, str_mbp_2018,
> +sizeof(str_mbp_2018)) &&
> +   (!memcmp(link->dpcd_caps.sink_fw_revision, fwrev_mbp_2018,
> +sizeof(fwrev_mbp_2018)) ||
> +   !memcmp(link->dpcd_caps.sink_fw_revision, 
> fwrev_mbp_2018_vega,
> +sizeof(fwrev_mbp_2018_vega {
> +   link->reported_link_cap.link_rate = LINK_RATE_RBR2;
> +   }
> +   }
> +
> memset(>dpcd_caps.dsc_caps, '\0',
> sizeof(link->dpcd_caps.dsc_caps));
> memset(>dpcd_caps.fec_cap, '\0', 
> sizeof(link->dpcd_caps.fec_cap));
> --
> 2.25.1
>
>

[PATCH v2] drm/amd/display: Force link_rate as LINK_RATE_RBR2 for 2018 15" Apple Retina panels

[Aditya Garg]

From: Aun-Ali Zaidi 
 
The eDP link rate reported by the DP_MAX_LINK_RATE dpcd register (0xa) is
contradictory to the highest rate supported reported by
EDID (0xc = LINK_RATE_RBR2). The effects of this compounded with commit
'4a8ca46bae8a ("drm/amd/display: Default max bpc to 16 for eDP")' results
in no display modes being found and a dark panel.

For now, simply force the maximum supported link rate for the eDP attached
2018 15" Apple Retina panels.

Additionally, we must also check the firmware revision since the device ID
reported by the DPCD is identical to that of the more capable 16,1,
incorrectly quirking it. We also use said firmware check to quirk the
refreshed 15,1 models with Vega graphics as they use a slightly newer
firmware version.

Tested-by: Aun-Ali Zaidi 
Reviewed-by: Harry Wentland 
Signed-off-by: Aun-Ali Zaidi 
Signed-off-by: Aditya Garg 
---
v2 :- Use C styled comments
 .../gpu/drm/amd/display/dc/core/dc_link_dp.c  | 20 +++
 1 file changed, 20 insertions(+)

diff --git a/drivers/gpu/drm/amd/display/dc/core/dc_link_dp.c 
b/drivers/gpu/drm/amd/display/dc/core/dc_link_dp.c
index 05e216524..086f7ee2c 100644
--- a/drivers/gpu/drm/amd/display/dc/core/dc_link_dp.c
+++ b/drivers/gpu/drm/amd/display/dc/core/dc_link_dp.c
@@ -5597,6 +5597,26 @@ static bool retrieve_link_cap(struct dc_link *link)
dp_hw_fw_revision.ieee_fw_rev,
sizeof(dp_hw_fw_revision.ieee_fw_rev));
 
+   /* Quirk for Apple MBP 2018 15" Retina panels: wrong DP_MAX_LINK_RATE */
+   {
+   uint8_t str_mbp_2018[] = { 101, 68, 21, 103, 98, 97 };
+   uint8_t fwrev_mbp_2018[] = { 7, 4 };
+   uint8_t fwrev_mbp_2018_vega[] = { 8, 4 };
+
+   /* We also check for the firmware revision as 16,1 models have 
an
+* identical device id and are incorrectly quirked otherwise.
+*/
+   if ((link->dpcd_caps.sink_dev_id == 0x0010fa) &&
+   !memcmp(link->dpcd_caps.sink_dev_id_str, str_mbp_2018,
+sizeof(str_mbp_2018)) &&
+   (!memcmp(link->dpcd_caps.sink_fw_revision, fwrev_mbp_2018,
+sizeof(fwrev_mbp_2018)) ||
+   !memcmp(link->dpcd_caps.sink_fw_revision, 
fwrev_mbp_2018_vega,
+sizeof(fwrev_mbp_2018_vega {
+   link->reported_link_cap.link_rate = LINK_RATE_RBR2;
+   }
+   }
+
memset(>dpcd_caps.dsc_caps, '\0',
sizeof(link->dpcd_caps.dsc_caps));
memset(>dpcd_caps.fec_cap, '\0', sizeof(link->dpcd_caps.fec_cap));
-- 
2.25.1