Re: [PATCH v4 1/5] fbdev: Avoid file argument in fb_pgprotect()

Thomas Zimmermann <tzimmermann@xxxxxxx> · Fri, 22 Sep 2023 09:40:55 +0200

Hi Javier

Am 20.09.23 um 10:01 schrieb Javier Martinez Canillas:

Thomas Zimmermann <tzimmermann@xxxxxxx> writes:

Hello Thomas,

Only PowerPC's fb_pgprotect() needs the file argument, although
the implementation does not use it. Pass NULL to the internal

Can you please mention the function that's the implementation for

Sure

PowerPC ? If I'm looking at the code correctly, that function is
phys_mem_access_prot() defined in the arch/powerpc/mm/mem.c file:

pgprot_t phys_mem_access_prot(struct file *file, unsigned long pfn,
			      unsigned long size, pgprot_t vma_prot)
{
	if (ppc_md.phys_mem_access_prot)
		return ppc_md.phys_mem_access_prot(file, pfn, size, vma_prot);

	if (!page_is_ram(pfn))
		vma_prot = pgprot_noncached(vma_prot);

	return vma_prot;
}

and if set, ppc_md.phys_mem_access_prot is pci_phys_mem_access_prot()
that is defined in the arch/powerpc/kernel/pci-common.c source file:

https://elixir.bootlin.com/linux/v6.6-rc2/source/arch/powerpc/kernel/pci-common.c#L524

Yes, that's correct. The only value for that function pointer appears to 

be pci_phys_mem_access_prot()

That function indeed doesn't use the file argument. So your patch looks
correct to me.

Reviewed-by: Javier Martinez Canillas <javierm@xxxxxxxxxx>

Thanks

Best regards
Thomas

--
Thomas Zimmermann
Graphics Driver Developer
SUSE Software Solutions Germany GmbH
Frankenstrasse 146, 90461 Nuernberg, Germany
GF: Ivo Totev, Andrew Myers, Andrew McDonald, Boudien Moerman
HRB 36809 (AG Nuernberg)

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