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authorSamasth Norway Ananda <samasth.norway.ananda@oracle.com>2026-03-16 16:19:19 -0700
committerJoonas Lahtinen <joonas.lahtinen@linux.intel.com>2026-03-23 09:06:36 +0200
commit08441f10f4dc09fdeb64529953ac308abc79dd38 (patch)
treec33197e3fd40274595c092223900c6cd1b9e7f44
parentc369299895a591d96745d6492d4888259b004a9e (diff)
drm/i915/gmbus: fix spurious timeout on 512-byte burst reads
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: d5dc0f43f268 ("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 4ab0f09ee73fc853d00466682635f67c531f909c) Signed-off-by: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
-rw-r--r--drivers/gpu/drm/i915/display/intel_gmbus.c4
1 files changed, 3 insertions, 1 deletions
diff --git a/drivers/gpu/drm/i915/display/intel_gmbus.c b/drivers/gpu/drm/i915/display/intel_gmbus.c
index a7bce0c6a17e..264e6843bff1 100644
--- a/drivers/gpu/drm/i915/display/intel_gmbus.c
+++ b/drivers/gpu/drm/i915/display/intel_gmbus.c
@@ -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;