Re: [PATCH v2 16/25] drm/mediatek: add ddp write register common api

CK Hu
2019-04-11T11:15:19Z

Hi, Yongqiang:

On Wed, 2019-03-27 at 14:19 +0800, yongqiang.niu@mediatek.com wrote:
> From: Yongqiang Niu <yongqiang.niu@mediatek.com>
>
> This patch add ddp write register common api
> this is preparation patch for ovl/ovl_2l direct link
> usecase.
> in that case, we need this funtion to set one bit of ovl_2l
> register

The reason is so strange. You could grep 'readl' in mediatek drm driver,
and you would find that many place need this function.

>
> Signed-off-by: Yongqiang Niu <yongqiang.niu@mediatek.com>
> ---
> drivers/gpu/drm/mediatek/mtk_drm_ddp_comp.c | 11 +++++++++++
> drivers/gpu/drm/mediatek/mtk_drm_ddp_comp.h | 4 ++++
> 2 files changed, 15 insertions(+)
>
> diff --git a/drivers/gpu/drm/mediatek/mtk_drm_ddp_comp.c b/drivers/gpu/drm/mediatek/mtk_drm_ddp_comp.c
> index afd6ca2..72288b4 100644
> --- a/drivers/gpu/drm/mediatek/mtk_drm_ddp_comp.c
> +++ b/drivers/gpu/drm/mediatek/mtk_drm_ddp_comp.c
> @@ -84,6 +84,17 @@
> #define DITHER_ADD_LSHIFT_G(x) (((x) & 0x7) << 4)
> #define DITHER_ADD_RSHIFT_G(x) (((x) & 0x7) << 0)
>
> +void mtk_ddp_write_mask(unsigned int value,
> + struct mtk_ddp_comp *comp,
> + unsigned int offset,
> + unsigned int mask)
> +{
> + unsigned int tmp = readl(comp->regs + offset);
> +
> + tmp = (tmp & ~mask) | (value & mask);

Why not just place this calculation into writel()?

Regards,
CK

> + writel(tmp, comp->regs + offset);
> +}
> +
> void mtk_dither_set(struct mtk_ddp_comp *comp, unsigned int bpc,
> unsigned int CFG)
> {
> diff --git a/drivers/gpu/drm/mediatek/mtk_drm_ddp_comp.h b/drivers/gpu/drm/mediatek/mtk_drm_ddp_comp.h
> index 20e8061..ed715ff 100644
> --- a/drivers/gpu/drm/mediatek/mtk_drm_ddp_comp.h
> +++ b/drivers/gpu/drm/mediatek/mtk_drm_ddp_comp.h
> @@ -198,5 +198,9 @@ int mtk_ddp_comp_init(struct device *dev, struct device_node *comp_node,
> void mtk_ddp_comp_unregister(struct drm_device *drm, struct mtk_ddp_comp *comp);
> void mtk_dither_set(struct mtk_ddp_comp *comp, unsigned int bpc,
> unsigned int CFG);
> +void mtk_ddp_write_mask(unsigned int value,
> + struct mtk_ddp_comp *comp,
> + unsigned int offset,
> + unsigned int mask);
>
> #endif /* MTK_DRM_DDP_COMP_H */