Re: [PATCH v1 1/4] video: simplefb-client: switch to dev_get_resource

[Ahmad Fatoum <a.fatoum@pengutronix.de>]

Hi Ivaylo,

thanks for your patch.

On 7/29/25 22:36, Ivaylo Ivanov wrote:
> Since the framebuffer memory resource resides in ram, it has already
> been requested and mapped, so only get the resource to avoid
> requesting a busy resource. This is also the approach for linux.

even if it's regular RAM (as opposed to video memory) we aren't
guaranteed, it's mapped suitably.

I think a remap of the region to writecombine is in order here. It
probably works right now, because we flush caches before shutting down
the MMU, but if you were to run fbtest, I'd expect that you will see
artifacts due to some pixels remaining in dirty cache line.

> While at it, use IOMEM for mem->start and drop an unnecessary newline.
> 
> Signed-off-by: Ivaylo Ivanov <ivo.ivanov.ivanov1@gmail.com>

Patch is correct, except for that aspect of the commit message:

Reviewed-by: Ahmad Fatoum <a.fatoum@pengutronix.de>

Thanks,
Ahmad

> ---
>  drivers/video/simplefb-client.c | 5 ++---
>  1 file changed, 2 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/video/simplefb-client.c b/drivers/video/simplefb-client.c
> index dafec617..41ad8ffa 100644
> --- a/drivers/video/simplefb-client.c
> +++ b/drivers/video/simplefb-client.c
> @@ -96,7 +96,7 @@ static int simplefb_probe(struct device *dev)
>  	if (ret)
>  		return ret;
>  
> -	mem = dev_request_mem_resource(dev, 0);
> +	mem = dev_get_resource(dev, IORESOURCE_MEM, 0);
>  	if (IS_ERR(mem)) {
>  		dev_err(dev, "No memory resource\n");
>  		return PTR_ERR(mem);
> @@ -116,10 +116,9 @@ static int simplefb_probe(struct device *dev)
>  	info->blue = params.format->blue;
>  	info->transp = params.format->transp;
>  
> -	info->screen_base = (void *)mem->start;
> +	info->screen_base = IOMEM(mem->start);
>  	info->screen_size = resource_size(mem);
>  
> -
>  	info->fbops = &simplefb_ops;
>  
>  	info->dev.parent = dev;

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