From: Nikola Cornij <nikola.cor...@amd.com>

[why]
Before a statically allocated PPS data structure, that did
get zeroed-out at startup, had been re-used for making packed PPS
SDP. With S3 fix, using a non-initialized PPS data structure was
introduced, while wrongly assuming it'd get initialized before it's
populated. As a consequence 'vbr_enable' and perhaps some other
fields are left uninitialized when making packed PPS SDP. This can
affect 'simple_422' as well because of the way PPS SDP packing is
done (the fields are not masked first, only shifted). The behavior
will be different, depending on the content of uninitialized data.

[how]
Zero-out PPS data structure at initialization time before it's
populated

Fixes:  3b87378c604e929015385e5cc76d0bbd55c05347
        drm/amd/display: Set DSC before DIG front-end is connected to its 
back-end

Signed-off-by: Nikola Cornij <nikola.cor...@amd.com>
Reviewed-by: Wenjing Liu <wenjing....@amd.com>
Acked-by: Bhawanpreet Lakha <bhawanpreet.la...@amd.com>
---
 drivers/gpu/drm/amd/display/dc/dcn20/dcn20_dsc.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/gpu/drm/amd/display/dc/dcn20/dcn20_dsc.c 
b/drivers/gpu/drm/amd/display/dc/dcn20/dcn20_dsc.c
index 379c9e4ac63b..c4f861e6bd53 100644
--- a/drivers/gpu/drm/amd/display/dc/dcn20/dcn20_dsc.c
+++ b/drivers/gpu/drm/amd/display/dc/dcn20/dcn20_dsc.c
@@ -447,6 +447,8 @@ static void dsc_init_reg_values(struct dsc_reg_values 
*reg_vals)
 {
        int i;
 
+       memset(reg_vals, 0, sizeof(struct dsc_reg_values));
+
        /* Non-PPS values */
        reg_vals->dsc_clock_enable            = 1;
        reg_vals->dsc_clock_gating_disable    = 0;
-- 
2.17.1

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