diff options
| author | Mikulas Patocka <mpatocka@redhat.com> | 2014-05-15 06:58:24 -0400 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2014-06-30 20:11:56 -0700 |
| commit | 4d7d9fb81084361ece363d6038bde2fdf9e9d510 (patch) | |
| tree | d1f805194a61efd4c8761beecfe7a573b0344d33 /drivers/video | |
| parent | 04e0002916df7668303e9ec855709327352fc9a2 (diff) | |
| download | lwn-4d7d9fb81084361ece363d6038bde2fdf9e9d510.tar.gz lwn-4d7d9fb81084361ece363d6038bde2fdf9e9d510.zip | |
matroxfb: perform a dummy read of M_STATUS
commit 972754cfaee94d6e25acf94a497bc0a864d91b7e upstream.
I had occasional screen corruption with the matrox framebuffer driver and
I found out that the reason for the corruption is that the hardware
blitter accesses the videoram while it is being written to.
The matrox driver has a macro WaitTillIdle() that should wait until the
blitter is idle, but it sometimes doesn't work. I added a dummy read
mga_inl(M_STATUS) to WaitTillIdle() to fix the problem. The dummy read
will flush the write buffer in the PCI chipset, and the next read of
M_STATUS will return the hardware status.
Since applying this patch, I had no screen corruption at all.
Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ti.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'drivers/video')
| -rw-r--r-- | drivers/video/matrox/matroxfb_base.h | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/drivers/video/matrox/matroxfb_base.h b/drivers/video/matrox/matroxfb_base.h index 556d96ce40bf..89a8a89a5eb2 100644 --- a/drivers/video/matrox/matroxfb_base.h +++ b/drivers/video/matrox/matroxfb_base.h @@ -698,7 +698,7 @@ void matroxfb_unregister_driver(struct matroxfb_driver* drv); #define mga_fifo(n) do {} while ((mga_inl(M_FIFOSTATUS) & 0xFF) < (n)) -#define WaitTillIdle() do {} while (mga_inl(M_STATUS) & 0x10000) +#define WaitTillIdle() do { mga_inl(M_STATUS); do {} while (mga_inl(M_STATUS) & 0x10000); } while (0) /* code speedup */ #ifdef CONFIG_FB_MATROX_MILLENIUM |