Hello Ivaylo,
On 7/30/25 13:28, Ivaylo Ivanov wrote:
> On 7/30/25 11:11, Ahmad Fatoum wrote:
>> 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.
>
> In my case at least, the mainline device tree covers all of dram -
> (0x80000000 + n GB)
>
>>
>> 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.
>
> So you suggest remapping it, like ipufb for example?
>
> fbi->info.screen_base = dma_alloc_writecombine(DMA_DEVICE_BROKEN,
> info->line_length * info->yres,
> DMA_ADDRESS_BROKEN);
Except for dma_alloc_writecombine allocating a new buffer instead of
remapping an existing region. See the patch I just Cc'd you on.
>>> While at it, use IOMEM for mem->start and drop an unnecessary newline.
>>>
>>> Signed-off-by: Ivaylo Ivanov <ivo.ivanov.ivan...@gmail.com>
>> Patch is correct, except for that aspect of the commit message:
>
> I don't get it, do I have to change the commit message only, or
> code logic too?
Just correct the commit message: s/Since/If/.
The writecombine thing is a separate issue.
Cheers,
Ahmad
>
> Thanks and best regards,
> Ivaylo
>
>>
>> Reviewed-by: Ahmad Fatoum <a.fat...@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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