Re: [PATCH v28 05/11] soc: mediatek: refine code to use mtk_mmsys_update_bits API

[Matthias Brugger <matthias.bgg@gmail.com>]

On 07/11/2022 08:22, Nancy.Lin wrote:
> Simplify code for update  mmsys reg.
> 
> Signed-off-by: Nancy.Lin <nancy.lin@mediatek.com>
> Reviewed-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
> Reviewed-by: CK Hu <ck.hu@mediatek.com>
> Tested-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
> Tested-by: Bo-Chen Chen <rex-bc.chen@mediatek.com>
> Reviewed-by: Nícolas F. R. A. Prado <nfraprado@collabora.com>
> ---
>   drivers/soc/mediatek/mtk-mmsys.c | 45 ++++++++++++--------------------
>   1 file changed, 16 insertions(+), 29 deletions(-)
> 
> diff --git a/drivers/soc/mediatek/mtk-mmsys.c b/drivers/soc/mediatek/mtk-mmsys.c
> index 9a327eb5d9d7..73c8bd27e6ae 100644
> --- a/drivers/soc/mediatek/mtk-mmsys.c
> +++ b/drivers/soc/mediatek/mtk-mmsys.c
> @@ -99,22 +99,27 @@ struct mtk_mmsys {
>   	struct reset_controller_dev rcdev;
>   };
>   
> +static void mtk_mmsys_update_bits(struct mtk_mmsys *mmsys, u32 offset, u32 mask, u32 val)
> +{
> +	u32 tmp;
> +
> +	tmp = readl_relaxed(mmsys->regs + offset);
> +	tmp = (tmp & ~mask) | (val & mask);

I'm not sure about the change in the implementation of mtk_mmsys_update_bits(). 
Nicolas tried to explain it to me on IRC but I wasn't totally convincing. As we 
have to go for at least another round of this patches, I'd like to get a clear 
understanding while it is needed that val bits are set to 1 in the mask.

Regards,
Matthias

> +	writel_relaxed(tmp, mmsys->regs + offset);
> +}
> +
>   void mtk_mmsys_ddp_connect(struct device *dev,
>   			   enum mtk_ddp_comp_id cur,
>   			   enum mtk_ddp_comp_id next)
>   {
>   	struct mtk_mmsys *mmsys = dev_get_drvdata(dev);
>   	const struct mtk_mmsys_routes *routes = mmsys->data->routes;
> -	u32 reg;
>   	int i;
>   
>   	for (i = 0; i < mmsys->data->num_routes; i++)
> -		if (cur == routes[i].from_comp && next == routes[i].to_comp) {
> -			reg = readl_relaxed(mmsys->regs + routes[i].addr);
> -			reg &= ~routes[i].mask;
> -			reg |= routes[i].val;
> -			writel_relaxed(reg, mmsys->regs + routes[i].addr);
> -		}
> +		if (cur == routes[i].from_comp && next == routes[i].to_comp)
> +			mtk_mmsys_update_bits(mmsys, routes[i].addr, routes[i].mask,
> +					      routes[i].val);
>   }
>   EXPORT_SYMBOL_GPL(mtk_mmsys_ddp_connect);
>   
> @@ -124,27 +129,14 @@ void mtk_mmsys_ddp_disconnect(struct device *dev,
>   {
>   	struct mtk_mmsys *mmsys = dev_get_drvdata(dev);
>   	const struct mtk_mmsys_routes *routes = mmsys->data->routes;
> -	u32 reg;
>   	int i;
>   
>   	for (i = 0; i < mmsys->data->num_routes; i++)
> -		if (cur == routes[i].from_comp && next == routes[i].to_comp) {
> -			reg = readl_relaxed(mmsys->regs + routes[i].addr);
> -			reg &= ~routes[i].mask;
> -			writel_relaxed(reg, mmsys->regs + routes[i].addr);
> -		}
> +		if (cur == routes[i].from_comp && next == routes[i].to_comp)
> +			mtk_mmsys_update_bits(mmsys, routes[i].addr, routes[i].mask, 0);
>   }
>   EXPORT_SYMBOL_GPL(mtk_mmsys_ddp_disconnect);
>   
> -static void mtk_mmsys_update_bits(struct mtk_mmsys *mmsys, u32 offset, u32 mask, u32 val)
> -{
> -	u32 tmp;
> -
> -	tmp = readl_relaxed(mmsys->regs + offset);
> -	tmp = (tmp & ~mask) | val;
> -	writel_relaxed(tmp, mmsys->regs + offset);
> -}
> -
>   void mtk_mmsys_ddp_dpi_fmt_config(struct device *dev, u32 val)
>   {
>   	if (val)
> @@ -161,18 +153,13 @@ static int mtk_mmsys_reset_update(struct reset_controller_dev *rcdev, unsigned l
>   {
>   	struct mtk_mmsys *mmsys = container_of(rcdev, struct mtk_mmsys, rcdev);
>   	unsigned long flags;
> -	u32 reg;
>   
>   	spin_lock_irqsave(&mmsys->lock, flags);
>   
> -	reg = readl_relaxed(mmsys->regs + mmsys->data->sw0_rst_offset);
> -
>   	if (assert)
> -		reg &= ~BIT(id);
> +		mtk_mmsys_update_bits(mmsys, mmsys->data->sw0_rst_offset, BIT(id), 0);
>   	else
> -		reg |= BIT(id);
> -
> -	writel_relaxed(reg, mmsys->regs + mmsys->data->sw0_rst_offset);
> +		mtk_mmsys_update_bits(mmsys, mmsys->data->sw0_rst_offset, BIT(id), BIT(id));
>   
>   	spin_unlock_irqrestore(&mmsys->lock, flags);
>