[PATCH] drm/amd/dc: Read from DP_SINK_COUNT_ESI for DPDC r1.2 or higher

[Wu, Hersen]

[AMD Official Use Only - Internal Distribution Only]



-----Original Message-----
From: Pillai, Aurabindo <Aurabindo.Pillai at amd.com> 
Sent: Tuesday, August 4, 2020 9:56 AM
To: Lin, Wayne <Wayne.Lin at amd.com>; amd-gfx at lists.freedesktop.org
Cc: Wu, Hersen <hersenxs.wu at amd.com>; Kazlauskas, Nicholas <Nicholas.Kazlauskas at amd.com>; Siqueira, Rodrigo <Rodrigo.Siqueira at amd.com>; Zuo, Jerry <Jerry.Zuo at amd.com>
Subject: Re: [PATCH] drm/amd/dc: Read from DP_SINK_COUNT_ESI for DPDC r1.2 or higher

On Tue, 2020-08-04 at 11:42 +0800, Wayne Lin wrote:
> [Why]
> According to DP spec, DPRX with DPCD r1.2 or higher shall have the 
> same Link/Sink Device Status field registers at DPCD Addresses 00200h 
> through 00205h to the corresponding DPRX Event Status Indicator 
> registers at DPCD Addresses 02002h through 0200Fh. We now only read 
> from 02002h when DPCD revision number is r1.4 or higher while handling 
> short HPD. Need to correct that.
> 
> [How]
> Set to read from 02002h when DPCD is r1.2 or higher
> 
> Signed-off-by: Wayne Lin <
> Wayne.Lin at amd.com
> >
> ---
>  drivers/gpu/drm/amd/display/dc/core/dc_link_dp.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> 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 2bfa4e35c2cf..9fb1543b4c73 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
> @@ -1834,9 +1834,9 @@ static enum dc_status read_hpd_rx_irq_data(
>  	 * fail, so we now explicitly read 6 bytes which is
>  	 * the req from the above mentioned test cases.
>  	 *
> -	 * For DP 1.4 we need to read those from 2002h range.
> +	 * For DPCD r1.2 or higher, we need to read those from 2002h
> range.
>  	 */
> -	if (link->dpcd_caps.dpcd_rev.raw < DPCD_REV_14)
> +	if (link->dpcd_caps.dpcd_rev.raw < DPCD_REV_12)
>  		retval = core_link_read_dpcd(
>  			link,
>  			DP_SINK_COUNT,

Reviewed-by: Aurabindo Pillai <aurabindo.pillai at amd.com>