Re: [PATCH v3 2/2] drm/bridge: analogix_dp: Add support for optional data-lanes mapping

[Damon Ding <damon.ding@rock-chips.com>]

Hi Luca,

On 5/26/2026 8:07 PM, Luca Ceresoli wrote:
> On Mon, 25 May 2026 17:47:31 +0800, Damon Ding <damon.ding@rock-chips.com> wrote:
> 
> Hello Damon,
> 
>>
>> diff --git a/drivers/gpu/drm/bridge/analogix/analogix_dp_core.c b/drivers/gpu/drm/bridge/analogix/analogix_dp_core.c
>> index 8cf6b73bceac..d53ab25bc57b 100644
>> --- a/drivers/gpu/drm/bridge/analogix/analogix_dp_core.c
>> +++ b/drivers/gpu/drm/bridge/analogix/analogix_dp_core.c
>> @@ -1234,6 +1234,59 @@ static const struct drm_bridge_funcs analogix_dp_bridge_funcs = {
>> [ ... skip 11 lines ... ]
>> +	int ret, i;
>> +
>> +	memcpy(video_info->lane_map, map, sizeof(map));
>> +
>> +	num_lanes = drm_of_get_data_lanes_count_ep(dp->dev->of_node, 1, 0, 1,
>> +						   video_info->max_lane_count);
> 
> Should num_lanes be > 4, the buffers could overflow. I realize it should
> not happen, but analogix_dp_dt_parse_pdata() can set max_lane_count from
> the device tree, so a bogus dtb could cause such overflow.
> 
> Perhaps you should just (in a separate patch) error out in
> analogix_dp_dt_parse_pdata() to prevent this. And maybe even adding an
> BUG_ON(lane_count > 4) here.
> 
> Otherwise LGTM.
> 

Thank you for the review.

I think it would be a better idea to add a separate patch to validate 
the max_link_rate and max_lane_count values for Exynos DP.

I checked the Exynos DP related DTS files:
- The maximum value of samsung,lane-count is 4
- The maximum value of samsung,link-rate is 0x0a, which corresponds to 
the HBR lane rate.

Could Marek please help confirm if we can set these as the upper limits 
for the checks?

Best regards,
Damon