[AMD Official Use Only - Internal Distribution Only]
-Original Message-
From: Pillai, Aurabindo
Sent: Tuesday, August 4, 2020 9:56 AM
To: Lin, Wayne ; amd-gfx@lists.freedesktop.org
Cc: Wu, Hersen ; Kazlauskas, Nicholas
; Siqueira, Rodrigo ;
Zuo, Jerry
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@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
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