From: Thomas Zimmermann <tzimmermann@suse.de>
To: Arnd Bergmann <arnd@arndb.de>,
Michael Ellerman <mpe@ellerman.id.au>,
Nicholas Piggin <npiggin@gmail.com>,
Christophe Leroy <christophe.leroy@csgroup.eu>,
Helge Deller <deller@gmx.de>
Cc: linuxppc-dev@lists.ozlabs.org, linux-fbdev@vger.kernel.org,
linux-ia64@vger.kernel.org, linux-m68k@lists.linux-m68k.org,
linux-mips@vger.kernel.org, sparclinux@vger.kernel.org,
dri-devel@lists.freedesktop.org,
Linux-Arch <linux-arch@vger.kernel.org>
Subject: Re: [PATCH v2 2/5] fbdev: Replace fb_pgprotect() with fb_pgprot_device()
Date: Thu, 7 Sep 2023 08:49:15 +0200 [thread overview]
Message-ID: <fc126f04-64f1-3403-2e12-54c723c68855@suse.de> (raw)
In-Reply-To: <8865aa0a-ec40-41ca-a77e-9172cec49f07@app.fastmail.com>
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Hi Arnd
Am 06.09.23 um 21:53 schrieb Arnd Bergmann:
> On Wed, Sep 6, 2023, at 10:35, Thomas Zimmermann wrote:
>> Rename the fbdev mmap helper fb_pgprotect() to fb_pgprot_device().
>> The helper sets VMA page-access flags for framebuffers in device I/O
>> memory. The new name follows pgprot_device(), which does the same for
>> arbitrary devices.
>>
>> Also clean up the helper's parameters and return value. Instead of
>> the VMA instance, pass the individial parameters separately: existing
>> page-access flags, the VMAs start and end addresses and the offset
>> in the underlying device memory rsp file. Return the new page-access
>> flags. These changes align fb_pgprot_device() closer with pgprot_device.
>>
>> Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
>
> This makes sense as a cleanup, but I'm not sure the new naming is helpful.
>
> The 'pgprot_device' permissions are based on Arm's memory attributes,
> which have slightly different behavior for "device", "uncached" and
> "writecombine" mappings. I think simply calling this one pgprot_fb()
> or fb_pgprot() would be less confusing, since depending on the architecture
> it appears to give either uncached or writecombine mappings but not
> "device" on the architectures where this is different.
I see. Thanks for the info. I like pgprot_fb() maybe
pgprot_framebuffer(). I'll update the patchset.
One thing I've been wondering is whether I should attempt to integrate
the helpers in <asm/fb.h> in the regular asm headers. So the pgprot code
would go into pgtable.h, the I/O functions would go into io.h. The I/O
functions could then be called readb_fb(), writel_fb(), memcpy_tofb()
and so on. Would you prefer that or rather not?
Best regards
Thomas
>
> Arnd
--
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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next prev parent reply other threads:[~2023-09-07 17:01 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-09-06 14:35 [PATCH v2 0/5] ppc, fbdev: Clean up fbdev mmap helper Thomas Zimmermann
2023-09-06 14:35 ` [PATCH v2 1/5] fbdev: Avoid file argument in fb_pgprotect() Thomas Zimmermann
2023-09-06 14:35 ` [PATCH v2 2/5] fbdev: Replace fb_pgprotect() with fb_pgprot_device() Thomas Zimmermann
2023-09-06 19:53 ` Arnd Bergmann
2023-09-07 6:49 ` Thomas Zimmermann [this message]
2023-09-06 14:35 ` [PATCH v2 3/5] arch/powerpc: Remove trailing whitespaces Thomas Zimmermann
2023-09-06 14:35 ` [PATCH v2 4/5] arch/powerpc: Remove file parameter from phys_mem_access_prot code Thomas Zimmermann
2023-09-06 14:35 ` [PATCH v2 5/5] arch/powerpc: Call internal __phys_mem_access_prot() in fbdev code Thomas Zimmermann
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