Re: [PATCH v2 2/7] drm/msm/hdmi: Handle msm_hdmi_power_on() errors during .atomic_pre_enable()

[Krzysztof Kozlowski <krzysztof.kozlowski@oss.qualcomm.com>]

On 07/09/2026 15:14, sashiko-bot@kernel.org wrote:
> Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
> - [High] Imprecise abort (kernel panic) in .atomic_post_disable() due to unclocked MMIO access after a failure in .atomic_pre_enable().
> --
> 
> commit 4f4c185244ef7ea6a900e7c373d8e29c18ab92a6
> Author: Krzysztof Kozlowski <krzysztof.kozlowski@oss.qualcomm.com>
> 
>     drm/msm/hdmi: Handle msm_hdmi_power_on() errors during .atomic_pre_enable()
>     
>     Properly handle power up failures during .atomic_pre_enable() by
>     aborting the .atomic_pre_enable() to avoid accessing registers why
>     blocks did not bring up.  Otherwise this could lead to imprecise aborts
>     when accessing MMIO while entire power domain is off.
> 
>> diff --git a/drivers/gpu/drm/msm/hdmi/hdmi_bridge.c b/drivers/gpu/drm/msm/hdmi/hdmi_bridge.c
>> index 157f19bd90b4e..db85400e574e4 100644
>> --- a/drivers/gpu/drm/msm/hdmi/hdmi_bridge.c
>> +++ b/drivers/gpu/drm/msm/hdmi/hdmi_bridge.c
> [ ... ]
>> @@ -287,13 +294,18 @@ static void msm_hdmi_bridge_atomic_pre_enable(struct drm_bridge *bridge,
>>  
>>  	msm_hdmi_set_timings(hdmi, &crtc_state->adjusted_mode);
>>  
>> -	mutex_lock(&hdmi->state_mutex);
>> -	if (!hdmi->power_on) {
>> -		msm_hdmi_phy_resource_enable(phy);
>> -		msm_hdmi_power_on(bridge);
>> -		hdmi->power_on = true;
>> +	scoped_guard(mutex, &hdmi->state_mutex) {
>> +		if (!hdmi->power_on) {
>> +			if (msm_hdmi_phy_resource_enable(phy))
>> +				return;
>> +
>> +			if (msm_hdmi_power_on(bridge)) {
>> +				msm_hdmi_phy_resource_disable(phy);
>> +				return;
>> +			}
>> +			hdmi->power_on = true;
>> +		}
>>  	}
> 
> [Severity: High]
> Does this early return cause an imprecise abort during atomic_post_disable()?
> 
> Since atomic_pre_enable() returns void, the DRM core will consider the state

That's a atomic_pre_enable() problem.

> committed even if it returns early here. This leaves hdmi->power_on = false
> and the PHY clocks and PM domain powered off.

Pre-existing design.


Best regards,
Krzysztof