Re: [PATCH v5 10/13] drm/mediatek: Support CRC in display driver

[Shawn Sung (宋孝謙)]

Hi Angelo,

On Thu, 2024-02-15 at 12:06 +0100, AngeloGioacchino Del Regno wrote:
> Il 15/02/24 11:11, Hsiao Chien Sung ha scritto:
> > Register CRC related function pointers to support
> > CRC retrieval.
> > 
> > Signed-off-by: Hsiao Chien Sung <shawn.sung@xxxxxxxxxxxx>
> > ---
> >   drivers/gpu/drm/mediatek/mtk_drm_crtc.c     | 239
> > ++++++++++++++++++++
> >   drivers/gpu/drm/mediatek/mtk_drm_crtc.h     |  39 ++++
> >   drivers/gpu/drm/mediatek/mtk_drm_ddp_comp.h |   3 +
> >   3 files changed, 281 insertions(+)
> > 
> > diff --git a/drivers/gpu/drm/mediatek/mtk_drm_crtc.c
> > b/drivers/gpu/drm/mediatek/mtk_drm_crtc.c
> > index 14cf75fa217f9..6cb1ed419dee7 100644
> > --- a/drivers/gpu/drm/mediatek/mtk_drm_crtc.c
> > +++ b/drivers/gpu/drm/mediatek/mtk_drm_crtc.c
> > @@ -68,6 +68,9 @@ struct mtk_drm_crtc {
> >   	/* lock for display hardware access */
> >   	struct mutex			hw_lock;
> >   	bool				config_updating;
> > +
> > +	struct mtk_ddp_comp		*crc_provider;
> > +	unsigned int			frames;
> >   };
> >   
> >   struct mtk_crtc_state {
> > @@ -635,6 +638,14 @@ static void mtk_crtc_ddp_irq(void *data)
> >   	struct drm_crtc *crtc = data;
> >   	struct mtk_drm_crtc *mtk_crtc = to_mtk_crtc(crtc);
> >   	struct mtk_drm_private *priv = crtc->dev->dev_private;
> > +	struct mtk_ddp_comp *comp = mtk_crtc->crc_provider;
> > +
> > +	/*
> > +	 * crc providers should make sure the crc is always correct
> > +	 * by resetting it in .crc_read()
> > +	 */
> > +	if (crtc->crc.opened)
> > +		comp->funcs->crc_read(comp->dev);
> >   
> >   #if IS_REACHABLE(CONFIG_MTK_CMDQ)
> >   	if (!priv->data->shadow_register && !mtk_crtc-
> > >cmdq_client.chan)
> > @@ -646,6 +657,24 @@ static void mtk_crtc_ddp_irq(void *data)
> >   	if (!priv->data->shadow_register)
> >   		mtk_crtc_ddp_config(crtc, NULL);
> >   #endif
> > +
> > +	/*
> > +	 * drm_crtc_add_crc_entry() could take more than 50ms to finish
> > +	 * put it at the end of the isr
> > +	 */
> > +	if (crtc->crc.opened) {
> > +		/*
> > +		 * skip the first crc because the first frame is
> > configured by
> > +		 * mtk_crtc_ddp_hw_init() when atomic enable
> > +		 */
> > +		if (++mtk_crtc->frames > 1) {
> > +			drm_crtc_add_crc_entry(crtc, true,
> > +					       drm_crtc_vblank_count(cr
> > tc),
> > +					       comp->funcs-
> > >crc_entry(comp->dev));
> > +		}
> > +	} else {
> > +		mtk_crtc->frames = 0;
> > +	}
> >   	mtk_drm_finish_page_flip(mtk_crtc);
> >   }
> >   
> > @@ -704,6 +733,40 @@ static void mtk_drm_crtc_update_output(struct
> > drm_crtc *crtc,
> >   	}
> >   }
> >   
> > +static int mtk_drm_crtc_set_crc_source(struct drm_crtc *crtc,
> > const char *src)
> > +{
> > +	if (src && strcmp(src, "auto") != 0) {
> > +		DRM_ERROR("%s(crtc-%d): unknown source '%s'\n",
> > +			  __func__, drm_crtc_index(crtc), src);
> > +		return -EINVAL;
> > +	}
> > +	return 0;
> > +}
> > +
> > +static int mtk_drm_crtc_verify_crc_source(struct drm_crtc *crtc,
> > +					  const char *src,
> > +					  size_t *cnt)
> > +{
> > +	struct mtk_drm_crtc *mtk_crtc = to_mtk_crtc(crtc);
> > +	struct mtk_ddp_comp *comp = mtk_crtc->crc_provider;
> > +
> > +	if (!comp) {
> > +		DRM_ERROR("%s(crtc-%d): no crc provider\n",
> > +			  __func__, drm_crtc_index(crtc));
> > +		return -ENOENT;
> > +	}
> > +
> > +	if (src && strcmp(src, "auto") != 0) {
> > +		DRM_ERROR("%s(crtc-%d): unknown source '%s'\n",
> > +			  __func__, drm_crtc_index(crtc), src);
> > +		return -EINVAL;
> > +	}
> > +
> > +	*cnt = comp->funcs->crc_cnt(comp->dev);
> > +
> > +	return 0;
> > +}
> > +
> >   int mtk_drm_crtc_plane_check(struct drm_crtc *crtc, struct
> > drm_plane *plane,
> >   			     struct mtk_plane_state *state)
> >   {
> > @@ -841,6 +904,8 @@ static const struct drm_crtc_funcs
> > mtk_crtc_funcs = {
> >   	.atomic_destroy_state	= mtk_drm_crtc_destroy_state,
> >   	.enable_vblank		= mtk_drm_crtc_enable_vblank,
> >   	.disable_vblank		= mtk_drm_crtc_disable_vblank,
> > +	.set_crc_source		= mtk_drm_crtc_set_crc_source,
> > +	.verify_crc_source	= mtk_drm_crtc_verify_crc_source,
> >   };
> >   
> >   static const struct drm_crtc_helper_funcs mtk_crtc_helper_funcs =
> > {
> > @@ -1033,6 +1098,11 @@ int mtk_drm_crtc_create(struct drm_device
> > *drm_dev,
> >   
> >   			if (comp->funcs->ctm_set)
> >   				has_ctm = true;
> > +
> > +			if (comp->funcs->crc_cnt &&
> > +			    comp->funcs->crc_entry &&
> > +			    comp->funcs->crc_read)
> > +				mtk_crtc->crc_provider = comp;
> >   		}
> >   
> >   		mtk_ddp_comp_register_vblank_cb(comp, mtk_crtc_ddp_irq,
> > @@ -1137,3 +1207,172 @@ int mtk_drm_crtc_create(struct drm_device
> > *drm_dev,
> >   
> >   	return 0;
> >   }
> > +
> > +void mtk_drm_crc_init(struct mtk_drm_crc *crc,
> > +		      const u32 *crc_offset_table, size_t crc_count,
> > +		      u32 reset_offset, u32 reset_mask)
> > +{
> > +	crc->ofs = crc_offset_table;
> > +	crc->cnt = crc_count;
> > +	crc->rst_ofs = reset_offset;
> > +	crc->rst_msk = reset_mask;
> > +	crc->va = kcalloc(crc->cnt, sizeof(*crc->va), GFP_KERNEL);
> > +	if (!crc->va) {
> > +		DRM_ERROR("failed to allocate memory for crc\n");
> > +		crc->cnt = 0;
> > +	}
> > +}
> > +
> > +void mtk_drm_crc_read(struct mtk_drm_crc *crc, void __iomem *reg)
> > +{
> 
> 	u32 n; goes here
> 
> > +	if (!crc->cnt || !crc->ofs || !crc->va)
> > +		return;
> > +
> > +#if IS_REACHABLE(CONFIG_MTK_CMDQ)
> > +	/* sync to see the most up-to-date copy of the DMA buffer */
> > +	dma_sync_single_for_cpu(crc->cmdq_client.chan->mbox->dev,
> > +				crc->pa, crc->cnt * sizeof(*crc->va),
> > +				DMA_FROM_DEVICE);
> > +#else
> > +	/* read crc with cpu for the platforms without cmdq */
> > +	{
> 
> then you don't need the braces.
> 
> Regards,
> Angelo
> 

The variable n is placed within the braces because when CONFIG_MTK_CMDQ
is defined, the variable is not being used and causes a build error.

This is a workaround in order to have only one #if macro in that
function for a more clean code.

Thanks,
Shawn