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    Subject[PATCH 3.2 012/125] matroxfb: perform a dummy read of M_STATUS
    3.2.61-rc1 review patch.  If anyone has any objections, please let me know.

    ------------------

    From: Mikulas Patocka <mpatocka@redhat.com>

    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>
    [bwh: Backported to 3.2: adjust filename]
    Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
    ---
    drivers/video/fbdev/matrox/matroxfb_base.h | 2 +-
    1 file changed, 1 insertion(+), 1 deletion(-)

    --- a/drivers/video/matrox/matroxfb_base.h
    +++ b/drivers/video/matrox/matroxfb_base.h
    @@ -698,7 +698,7 @@ void matroxfb_unregister_driver(struct m

    #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


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