Re: [PATCH 3/3] jz4740_fb: fix DMA API abuse

From: Bartlomiej Zolnierkiewicz
Date: Fri Jun 21 2019 - 07:32:23 EST



Hi,

On 6/7/19 2:21 PM, Bartlomiej Zolnierkiewicz wrote:
>
> On 5/9/19 7:38 PM, Christoph Hellwig wrote:
>> Virtual addresses return from dma(m)_alloc_coherent are opaque in what
>> backs then, and drivers must not poke into them. Switch the driver
>> to use the generic DMA API mmap helper to avoid these problems.
> Change itself looks fine but the patch description doesn't match what
> the patch is actually doing (there is no conversion to DMA API helper
> because the driver is already using it). Please correct it. Thank you.

I've just removed the "Switch the driver.." sentence myself from
the patch description and applied the change, thanks!

>> Signed-off-by: Christoph Hellwig <hch@xxxxxx>
>> ---
>> drivers/video/fbdev/jz4740_fb.c | 7 -------
>> 1 file changed, 7 deletions(-)
>> diff --git a/drivers/video/fbdev/jz4740_fb.c b/drivers/video/fbdev/jz4740_fb.c
>> index b57df83fdbd3..b95cdfa9e0a1 100644
>> --- a/drivers/video/fbdev/jz4740_fb.c
>> +++ b/drivers/video/fbdev/jz4740_fb.c
>> @@ -466,7 +466,6 @@ static int jzfb_alloc_devmem(struct jzfb *jzfb)
>> {
>> int max_videosize = 0;
>> struct fb_videomode *mode = jzfb->pdata->modes;
>> - void *page;
>> int i;
>>
>> for (i = 0; i < jzfb->pdata->num_modes; ++mode, ++i) {
>> @@ -491,12 +490,6 @@ static int jzfb_alloc_devmem(struct jzfb *jzfb)
>> if (!jzfb->vidmem)
>> goto err_free_framedesc;
>>
>> - for (page = jzfb->vidmem;
>> - page < jzfb->vidmem + PAGE_ALIGN(jzfb->vidmem_size);
>> - page += PAGE_SIZE) {
>> - SetPageReserved(virt_to_page(page));
>> - }
>> -
>> jzfb->framedesc->next = jzfb->framedesc_phys;
>> jzfb->framedesc->addr = jzfb->vidmem_phys;
>> jzfb->framedesc->id = 0xdeafbead;
Best regards,
--
Bartlomiej Zolnierkiewicz
Samsung R&D Institute Poland
Samsung Electronics