[Intel-gfx] [PATCH] drm/i915: Switch LSPCON to PCON mode if it's in LS mode

[Sharma, Shashank]

Regards

Shashank


On 11/7/2018 10:48 PM, Ville Syrjala wrote:
> From: Ville Syrjälä <ville.syrjala at linux.intel.com>
>
> We no longer change LSPCON into PCON mode if it boots up in
> LS mode. This was broken by some code shuffling in
> commit 96e35598cead ("drm/i915: Check LSPCON vendor OUI").
>
> I actually can't see a reason why that code shuffling had
> to be done. The commit msg notes it but doesn't justify it
> in any way.
Its been some time, but AFAIR this shuffling was done because we wanted 
to make sure LSPCON is in DP/PCON personality, before we try to read 
DCPD and vendor OUI. I probably missed to add this reason in commit 
message. There were few LSPCON devices, which due to old FW version, or 
some one or other reason, were booting in LS mode. We wanted to make 
sure that probing, mode change and delay related stuff is all taken care 
in lspcon_probe function, and after probing, LSPCON is ready to be used 
in PCON personality.
>   But I guess we'll keep the code in its current
> place anyway and just make the "switch to PCON mode" part
> effective once again.
>
> Cc: Shashank Sharma <shashank.sharma at intel.com>
> Cc: Maarten Lankhorst <maarten.lankhorst at linux.intel.com>
> Cc: Tvrtko Ursulin <tvrtko.ursulin at linux.intel.com>
> Tested-by: Tvrtko Ursulin <tvrtko.ursulin at linux.intel.com>
> Fixes: 96e35598cead ("drm/i915: Check LSPCON vendor OUI")
> Signed-off-by: Ville Syrjälä <ville.syrjala at linux.intel.com>
> ---
>   drivers/gpu/drm/i915/intel_lspcon.c | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/gpu/drm/i915/intel_lspcon.c b/drivers/gpu/drm/i915/intel_lspcon.c
> index fff32b31c7df..96a8d9524b0c 100644
> --- a/drivers/gpu/drm/i915/intel_lspcon.c
> +++ b/drivers/gpu/drm/i915/intel_lspcon.c
> @@ -230,7 +230,7 @@ static bool lspcon_probe(struct intel_lspcon *lspcon)
>   	 * In this way, it will work with both HDMI 1.4 sinks as well as HDMI
>   	 * 2.0 sinks.
>   	 */
> -	if (lspcon->active && lspcon->mode != DRM_LSPCON_MODE_PCON) {
> +	if (lspcon->mode != DRM_LSPCON_MODE_PCON) {
Agree, this became irrelevant once we added the vendor detection code, 
and decided to call it active, only when probing, dpcd_read and 
vendor_detection is all good.
Reviewed-by: Shashank Sharma <shashank.sharma at intel.com>
>   		if (lspcon_change_mode(lspcon, DRM_LSPCON_MODE_PCON) < 0) {
>   			DRM_ERROR("LSPCON mode change to PCON failed\n");
>   			return false;

- Shashank