[PATCH v2] gpu: ipu-v3: pre: only use internal clock gating

[Philipp Zabel]

On Wed, 2017-05-03 at 10:38 +0200, Lucas Stach wrote:
> By setting the SFTRST bit, the PRE will be held in the lowest power state
> with clocks to the internal blocks gated. When external clock gating is
> used (from the external clock controller, or by setting the CLKGATE bit)
> the PRE will sporadically fail to start.
> 
> Signed-off-by: Lucas Stach <l.stach at pengutronix.de>
> ---
> v2: add missing clk_disable_unprepare in remove path
> 
> This is a fix for newly introduced functionality and should be applied
> for 4.12 fixes.
> ---
>  drivers/gpu/ipu-v3/ipu-pre.c | 13 +++++--------
>  1 file changed, 5 insertions(+), 8 deletions(-)
> 
> diff --git a/drivers/gpu/ipu-v3/ipu-pre.c b/drivers/gpu/ipu-v3/ipu-pre.c
> index c55563379e2e..c35f74c83065 100644
> --- a/drivers/gpu/ipu-v3/ipu-pre.c
> +++ b/drivers/gpu/ipu-v3/ipu-pre.c
> @@ -131,8 +131,6 @@ int ipu_pre_get(struct ipu_pre *pre)
>  	if (pre->in_use)
>  		return -EBUSY;
>  
> -	clk_prepare_enable(pre->clk_axi);
> -
>  	/* first get the engine out of reset and remove clock gating */
>  	writel(0, pre->regs + IPU_PRE_CTRL);
>  
> @@ -149,12 +147,7 @@ int ipu_pre_get(struct ipu_pre *pre)
>  
>  void ipu_pre_put(struct ipu_pre *pre)
>  {
> -	u32 val;
> -
> -	val = IPU_PRE_CTRL_SFTRST | IPU_PRE_CTRL_CLKGATE;
> -	writel(val, pre->regs + IPU_PRE_CTRL);
> -
> -	clk_disable_unprepare(pre->clk_axi);
> +	writel(IPU_PRE_CTRL_SFTRST, pre->regs + IPU_PRE_CTRL);
>  
>  	pre->in_use = false;
>  }
> @@ -249,6 +242,8 @@ static int ipu_pre_probe(struct platform_device *pdev)
>  	if (!pre->buffer_virt)
>  		return -ENOMEM;
>  
> +	clk_prepare_enable(pre->clk_axi);
> +
>  	pre->dev = dev;
>  	platform_set_drvdata(pdev, pre);
>  	mutex_lock(&ipu_pre_list_mutex);
> @@ -268,6 +263,8 @@ static int ipu_pre_remove(struct platform_device *pdev)
>  	available_pres--;
>  	mutex_unlock(&ipu_pre_list_mutex);
>  
> +	clk_disable_unprepare(pre->clk_axi);
> +

Thank you. I've applied this patch to imx-drm/fixes.

regards
Philipp