Re: [PATCH 5/6] drm/rcar_du: use drm_encoder pointer for drm_writeback_connector

[Abhinav Kumar]

Hi Laurent

On 3/10/2022 11:28 PM, Laurent Pinchart wrote:
Hi Abhinav
Thank you for the patch.

On Thu, Mar 10, 2022 at 05:49:59PM -0800, Abhinav Kumar wrote:
Make changes to rcar_du driver to start using drm_encoder pointer
for drm_writeback_connector.

Co-developed-by: Kandpal Suraj <suraj.kand...@intel.com>
Signed-off-by: Abhinav Kumar <quic_abhin...@quicinc.com>
---
  drivers/gpu/drm/rcar-du/rcar_du_writeback.c | 3 ++-
  1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/rcar-du/rcar_du_writeback.c 
b/drivers/gpu/drm/rcar-du/rcar_du_writeback.c
index c79d125..03930ad 100644
--- a/drivers/gpu/drm/rcar-du/rcar_du_writeback.c
+++ b/drivers/gpu/drm/rcar-du/rcar_du_writeback.c
@@ -200,7 +200,8 @@ int rcar_du_writeback_init(struct rcar_du_device *rcdu,
  {
        struct drm_writeback_connector *wb_conn = &rcrtc->writeback;
  
-	wb_conn->encoder.possible_crtcs = 1 << drm_crtc_index(&rcrtc->crtc);
+       wb_conn->encoder = kzalloc(sizeof(struct drm_encoder), GFP_KERNEL);

Where is this freed ?

You are right, this isnt. Looking more into this, it seems like moving 
the allocation of encoder to drm_writeback.c for cases which dont pass a 
real encoder is much better so that I will not have to add alloc() / 
free() code for all the vendor driver changes which is what I originally 
thought in my RFC but changed my mind because of below.


+       wb_conn->encoder->possible_crtcs = 1 << drm_crtc_index(&rcrtc->crtc);

Do you think we can just move usage of wb_conn->encoder->possible_crtcs 
just right after drm_writeback_connector_init() so that it wont crash?

198 int rcar_du_writeback_init(struct rcar_du_device *rcdu,
199                        struct rcar_du_crtc *rcrtc)
200 {
201     struct drm_writeback_connector *wb_conn = &rcrtc->writeback;
202
203     wb_conn->encoder.possible_crtcs = 1 << drm_crtc_index(&rcrtc->crtc);
204     drm_connector_helper_add(&wb_conn->base,
205                              &rcar_du_wb_conn_helper_funcs);
206
207     return drm_writeback_connector_init(&rcdu->ddev, wb_conn,
208                                         &rcar_du_wb_conn_funcs,
209                                         &rcar_du_wb_enc_helper_funcs,
210                                         writeback_formats,
211                                         ARRAY_SIZE(writeback_formats));
212 }

        drm_connector_helper_add(&wb_conn->base,
                                 &rcar_du_wb_conn_helper_funcs);