| From dcf9070595e100942c539e229dde4770aaeaa4e9 Mon Sep 17 00:00:00 2001 |
| From: Yifeng Li <tomli@tomli.me> |
| Date: Mon, 1 Apr 2019 17:46:58 +0200 |
| Subject: fbdev: sm712fb: fix VRAM detection, don't set SR70/71/74/75 |
| |
| From: Yifeng Li <tomli@tomli.me> |
| |
| commit dcf9070595e100942c539e229dde4770aaeaa4e9 upstream. |
| |
| On a Thinkpad s30 (Pentium III / i440MX, Lynx3DM), the amount of Video |
| RAM is not detected correctly by the xf86-video-siliconmotion driver. |
| This is because sm712fb overwrites the GPR71 Scratch Pad Register, which |
| is set by BIOS on x86 and used to indicate amount of VRAM. |
| |
| Other Scratch Pad Registers, including GPR70/74/75, don't have the same |
| side-effect, but overwriting to them is still questionable, as they are |
| not related to modesetting. |
| |
| Stop writing to SR70/71/74/75 (a.k.a GPR70/71/74/75). |
| |
| Signed-off-by: Yifeng Li <tomli@tomli.me> |
| Tested-by: Sudip Mukherjee <sudipm.mukherjee@gmail.com> |
| Cc: Teddy Wang <teddy.wang@siliconmotion.com> |
| Cc: <stable@vger.kernel.org> # v4.4+ |
| Signed-off-by: Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com> |
| Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> |
| |
| --- |
| drivers/video/fbdev/sm712fb.c | 4 +++- |
| 1 file changed, 3 insertions(+), 1 deletion(-) |
| |
| --- a/drivers/video/fbdev/sm712fb.c |
| +++ b/drivers/video/fbdev/sm712fb.c |
| @@ -1145,7 +1145,9 @@ static void sm7xx_set_timing(struct smtc |
| /* init SEQ register SR30 - SR75 */ |
| for (i = 0; i < SIZE_SR30_SR75; i++) |
| if ((i + 0x30) != 0x30 && (i + 0x30) != 0x62 && |
| - (i + 0x30) != 0x6a && (i + 0x30) != 0x6b) |
| + (i + 0x30) != 0x6a && (i + 0x30) != 0x6b && |
| + (i + 0x30) != 0x70 && (i + 0x30) != 0x71 && |
| + (i + 0x30) != 0x74 && (i + 0x30) != 0x75) |
| smtc_seqw(i + 0x30, |
| vgamode[j].init_sr30_sr75[i]); |
| |
