| From 972754cfaee94d6e25acf94a497bc0a864d91b7e Mon Sep 17 00:00:00 2001 |
| From: Mikulas Patocka <mpatocka@redhat.com> |
| Date: Thu, 15 May 2014 06:58:24 -0400 |
| Subject: matroxfb: perform a dummy read of M_STATUS |
| |
| 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> |
| Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> |
| |
| --- |
| drivers/video/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 |
