31 Jul
2023
31 Jul
'23
7:08 p.m.
On Mon, 31 Jul 2023 at 00:03, Bin Meng bmeng@tinylab.org wrote:
From: Bin Meng bmeng.cn@gmail.com
At present this uses mtrr_add_request() & mtrr_commit() combination to program the MTRR for graphics memory. This usage has two major issues as below:
- mtrr_commit() will re-initialize all MTRR registers from index 0, using the settings previously added by mtrr_add_request() and saved in gd->arch.mtrr_req[], which won't cause any issue but is unnecessary
- The way such combination works is based on the assumption that U-Boot has full control with MTRR programming (e.g.: U-Boot without any blob that does all low-level initialization on its own, or using FSP2 which does not touch MTRR), but this is not the case with FSP. FSP programs some MTRRs during its execution but U-Boot does not have the settings saved in gd->arch.mtrr_req[] and when doing mtrr_commit() it will corrupt what was already programmed previously.
Correct this to use mtrr_set_next_var() instead.
Signed-off-by: Bin Meng bmeng.cn@gmail.com
(no changes since v1)
drivers/video/broadwell_igd.c | 10 +++------- 1 file changed, 3 insertions(+), 7 deletions(-)
Reviewed-by: Simon Glass sjg@chromium.org