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drm/i915/gmbus: fix spurious timeout on 512-byte burst reads

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When reading exactly 512 bytes with burst read enabled, the
extra_byte_added path breaks out of the inner do-while without
decrementing len. The outer while(len) then re-enters and gmbus_wait()
times out since all data has been delivered. Decrement len before the
break so the outer loop terminates correctly.

Fixes: d5dc0f43f2 ("drm/i915/gmbus: Enable burst read")
Signed-off-by: Samasth Norway Ananda <samasth.norway.ananda@oracle.com>
Reviewed-by: Jani Nikula <jani.nikula@intel.com>
Link: https://patch.msgid.link/20260316231920.135438-2-samasth.norway.ananda@oracle.com
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
(cherry picked from commit 4ab0f09ee7)
Signed-off-by: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
This commit is contained in:
Samasth Norway Ananda
2026-03-16 16:19:19 -07:00
committed by Joonas Lahtinen
parent c369299895
commit 08441f10f4
1 changed files with 3 additions and 1 deletions
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4
drivers/gpu/drm/i915/display/intel_gmbus.c
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@@ -496,8 +496,10 @@ gmbus_xfer_read_chunk(struct intel_display *display,
val = intel_de_read_fw(display, GMBUS3(display));
do {
if (extra_byte_added && len == 1)
if (extra_byte_added && len == 1) {
len--;
break;
}
*buf++ = val & 0xff;
val >>= 8;