[PATCH v3 03/14] drm/rockchip: analogix_dp: Apply drmm_encoder_init() instead of drm_simple_encoder_init()

[Damon Ding]

Hi Dmitry,

On 2025/7/26 8:12, Dmitry Baryshkov wrote:
> On Thu, Jul 24, 2025 at 04:02:53PM +0800, Damon Ding wrote:
>> Compared with drm_simple_encoder_init(), drmm_encoder_init() can handle
>> the cleanup automatically through registering drm_encoder_cleanup() with
>> drmm_add_action().
>>
>> Signed-off-by: Damon Ding <damon.ding at rock-chips.com>
>> ---
>>   drivers/gpu/drm/rockchip/analogix_dp-rockchip.c | 4 +---
>>   1 file changed, 1 insertion(+), 3 deletions(-)
>>
>> diff --git a/drivers/gpu/drm/rockchip/analogix_dp-rockchip.c b/drivers/gpu/drm/rockchip/analogix_dp-rockchip.c
>> index d30f0983a53a..4ed6bf9e5377 100644
>> --- a/drivers/gpu/drm/rockchip/analogix_dp-rockchip.c
>> +++ b/drivers/gpu/drm/rockchip/analogix_dp-rockchip.c
>> @@ -29,7 +29,6 @@
>>   #include <drm/drm_of.h>
>>   #include <drm/drm_panel.h>
>>   #include <drm/drm_probe_helper.h>
>> -#include <drm/drm_simple_kms_helper.h>
>>   
>>   #include "rockchip_drm_drv.h"
>>   
>> @@ -377,8 +376,7 @@ static int rockchip_dp_drm_create_encoder(struct rockchip_dp_device *dp)
>>   							     dev->of_node);
>>   	DRM_DEBUG_KMS("possible_crtcs = 0x%x\n", encoder->possible_crtcs);
>>   
>> -	ret = drm_simple_encoder_init(drm_dev, encoder,
>> -				      DRM_MODE_ENCODER_TMDS);
>> +	ret = drmm_encoder_init(drm_dev, encoder, NULL, DRM_MODE_ENCODER_TMDS, NULL);
> 
> It's not possible to use drmm_encoder_init() here. Per the documentation
> the encoder data structure should be allocated by drmm_kzalloc().
> However this drm_encoder is a part of struct rockchip_dp_device. It's
> allocated by rockchip_dp_probe() via devm_kzalloc(). This means that it
> can potentially be freed before the drm device is completely released,
> creating a use-after-free error.
> 
>>   	if (ret) {
>>   		DRM_ERROR("failed to initialize encoder with drm\n");
>>   		return ret;
>> -- 
>> 2.34.1
>>
> 

Got it. This patch will be dropped in the next version.

Best regards,
Damon