From: Pavel Machek <pavel@ucw.cz>
To: Dave Airlie <airlied@redhat.com>
Cc: torvalds@linux-foundation.org, linux-kernel@vger.kernel.org,
dri-devel@lists.sf.net
Subject: Re: [PATCH] vt_buffer: drop console buffer copying optimisations
Date: Tue, 24 Feb 2015 17:49:15 +0100 [thread overview]
Message-ID: <20150224164914.GA6683@amd> (raw)
In-Reply-To: <1422504685-7864-1-git-send-email-airlied@redhat.com>
On Thu 2015-01-29 14:11:25, Dave Airlie wrote:
> These two copy to/from VGA memory, however on the Silicon
> Motion SMI750 VGA card on a 64-bit system cause console corruption.
>
> This is due to the hw being buggy and not handling a 64-bit transaction
> correctly.
>
> We could try and create a 32-bit version of these routines,
> but I'm not sure the optimisation is worth much today.
>
> Fixes https://bugzilla.redhat.com/show_bug.cgi?id=1132826
>
> Tested-by: Huawei engineering.
> Signed-off-by: Dave Airlie <airlied@redhat.com>
Actually... are you sure this is right fix?
IOW can gcc do the optimalization behind your back and still break the
buggy card?
Pavel
> diff --git a/include/linux/vt_buffer.h b/include/linux/vt_buffer.h
> index 057db7d..f38c10b 100644
> --- a/include/linux/vt_buffer.h
> +++ b/include/linux/vt_buffer.h
> @@ -21,10 +21,6 @@
> #ifndef VT_BUF_HAVE_RW
> #define scr_writew(val, addr) (*(addr) = (val))
> #define scr_readw(addr) (*(addr))
> -#define scr_memcpyw(d, s, c) memcpy(d, s, c)
> -#define scr_memmovew(d, s, c) memmove(d, s, c)
> -#define VT_BUF_HAVE_MEMCPYW
> -#define VT_BUF_HAVE_MEMMOVEW
> #endif
>
> #ifndef VT_BUF_HAVE_MEMSETW
--
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html
prev parent reply other threads:[~2015-02-24 16:49 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-01-29 4:11 [PATCH] vt_buffer: drop console buffer copying optimisations Dave Airlie
2015-01-29 12:06 ` Peter Hurley
2015-01-29 23:40 ` Linus Torvalds
2015-01-29 23:57 ` Greg Kroah-Hartman
2015-01-30 0:03 ` Linus Torvalds
2015-01-30 0:14 ` Dave Airlie
2015-02-03 15:54 ` One Thousand Gnomes
2015-02-05 9:01 ` Geert Uytterhoeven
2015-02-05 11:35 ` One Thousand Gnomes
2015-02-09 10:35 ` Daniel Stone
2015-02-09 10:49 ` Geert Uytterhoeven
2015-02-09 11:00 ` Daniel Stone
2015-02-09 20:17 ` One Thousand Gnomes
2015-02-24 16:49 ` Pavel Machek [this message]
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