Re: [PATCH 2/2] clk: mediatek: mux: Update parent at enable time

[Weiyi Lu <weiyi.lu@mediatek.com>]

On Mon, 2021-01-25 at 19:08 +0200, Laurent Pinchart wrote:
> The mux clocks don't always correctly take the new parent into account
> when the parent is updated while the clock is disabled. Set the update
> bit when enabling the clock to force an update of the mux.
> 
> Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>

Hi Laurent,

Thank you for the patch. Looks good to me.
Reviewed-by: Weiyi Lu <weiyi.lu@mediatek.com>

> ---
>  drivers/clk/mediatek/clk-mux.c | 32 +++++++++++++++++++++++++++++---
>  drivers/clk/mediatek/clk-mux.h |  1 +
>  2 files changed, 30 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/clk/mediatek/clk-mux.c b/drivers/clk/mediatek/clk-mux.c
> index 9370bebca7f8..b0c61709bacc 100644
> --- a/drivers/clk/mediatek/clk-mux.c
> +++ b/drivers/clk/mediatek/clk-mux.c
> @@ -20,9 +20,33 @@ static inline struct mtk_clk_mux *to_mtk_clk_mux(struct clk_hw *hw)
>  static int mtk_clk_mux_enable_setclr(struct clk_hw *hw)
>  {
>  	struct mtk_clk_mux *mux = to_mtk_clk_mux(hw);
> +	unsigned long flags = 0;
>  
> -	return regmap_write(mux->regmap, mux->data->clr_ofs,
> -			BIT(mux->data->gate_shift));
> +	if (mux->lock)
> +		spin_lock_irqsave(mux->lock, flags);
> +	else
> +		__acquire(mux->lock);
> +
> +	regmap_write(mux->regmap, mux->data->clr_ofs,
> +		     BIT(mux->data->gate_shift));
> +
> +	/*
> +	 * If the parent has been changed when the clock was disabled, it will
> +	 * not be effective yet. Set the update bit to ensure the mux gets
> +	 * updated.
> +	 */
> +	if (mux->reparent && mux->data->upd_shift >= 0) {
> +		regmap_write(mux->regmap, mux->data->upd_ofs,
> +			     BIT(mux->data->upd_shift));
> +		mux->reparent = false;
> +	}
> +
> +	if (mux->lock)
> +		spin_unlock_irqrestore(mux->lock, flags);
> +	else
> +		__release(mux->lock);
> +
> +	return 0;
>  }
>  
>  static void mtk_clk_mux_disable_setclr(struct clk_hw *hw)
> @@ -77,9 +101,11 @@ static int mtk_clk_mux_set_parent_setclr_lock(struct clk_hw *hw, u8 index)
>  		regmap_write(mux->regmap, mux->data->set_ofs,
>  				index << mux->data->mux_shift);
>  
> -		if (mux->data->upd_shift >= 0)
> +		if (mux->data->upd_shift >= 0) {
>  			regmap_write(mux->regmap, mux->data->upd_ofs,
>  					BIT(mux->data->upd_shift));
> +			mux->reparent = true;
> +		}
>  	}
>  
>  	if (mux->lock)
> diff --git a/drivers/clk/mediatek/clk-mux.h b/drivers/clk/mediatek/clk-mux.h
> index 15c62366ba9a..f1946161ade1 100644
> --- a/drivers/clk/mediatek/clk-mux.h
> +++ b/drivers/clk/mediatek/clk-mux.h
> @@ -14,6 +14,7 @@ struct mtk_clk_mux {
>  	struct regmap *regmap;
>  	const struct mtk_mux *data;
>  	spinlock_t *lock;
> +	bool reparent;
>  };
>  
>  struct mtk_mux {