On 2021-10-20 12:35 p.m., Kent Russell wrote:
Currently dmesg doesn't warn when the number of bad pages approaches the
threshold for page retirement. WARN when the number of bad pages
is at 90% or greater for easier checks and planning, instead of waiting
until the GPU is full of bad pages

Cc: Luben Tuikov <luben.tui...@amd.com>
Cc: Mukul Joshi <mukul.jo...@amd.com>
Signed-off-by: Kent Russell <kent.russ...@amd.com>
---
  drivers/gpu/drm/amd/amdgpu/amdgpu_ras_eeprom.c | 17 +++++++++++++++++
  1 file changed, 17 insertions(+)

diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_ras_eeprom.c 
b/drivers/gpu/drm/amd/amdgpu/amdgpu_ras_eeprom.c
index f4c05ff4b26c..1ede0f0d6f55 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_ras_eeprom.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_ras_eeprom.c
@@ -1071,12 +1071,29 @@ int amdgpu_ras_eeprom_init(struct 
amdgpu_ras_eeprom_control *control,
        control->ras_fri = RAS_OFFSET_TO_INDEX(control, hdr->first_rec_offset);
if (hdr->header == RAS_TABLE_HDR_VAL) {
+               int threshold = 0;

ras->bad_page_cnt_threshold is uint32_t. I'd recommend using the same type. Also add an empty line after the declaration to avoid a checkpatch warning.


                DRM_DEBUG_DRIVER("Found existing EEPROM table with %d records",
                                 control->ras_num_recs);
                res = __verify_ras_table_checksum(control);
                if (res)
                        DRM_ERROR("RAS table incorrect checksum or error:%d\n",
                                  res);
+
+               /* threshold = 0 means that page retirement is disabled, while
+                * threshold = -1 means default behaviour
+                */
+               if (amdgpu_bad_page_threshold == -1)
+                       threshold = ras->bad_page_cnt_threshold;
+               else if (amdgpu_bad_page_threshold > 0)
+                       threshold = amdgpu_bad_page_threshold;
+
+               /* Since multiplcation is transitive, a = 9b/10 is the same
+                * as 10a = 9b. Use this for our 90% limit to avoid rounding
+                */
+               if (threshold > 0 && ((control->ras_num_recs * 10) >= 
(threshold * 9)))

Not sure how big these values can get, but you may need to cast to (uint64_t) before the multiplications to avoid overflows. Alternatively you could use (control->ras_num_recs / 9 >= threshold / 10). It'll round, but never overflow.


+                       DRM_WARN("RAS records:%u exceeds 90%% of threshold:%d",

Nitpick: I'd add space after the two colons for readability. The threshold should use %u if you make it uint32_t. This can never be negative.

Regards,
  Felix


+                                       control->ras_num_recs,
+                                       threshold);
        } else if (hdr->header == RAS_TABLE_HDR_BAD &&
                   amdgpu_bad_page_threshold != 0) {
                res = __verify_ras_table_checksum(control);

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