linux-kernel - [PATCH] drm/i915/gvt: Fix bug in getting msg length in AUX CH registers handler

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Message-Id: <20230731112033.7275-1-yan.y.zhao@intel.com>
Date:   Mon, 31 Jul 2023 19:20:33 +0800
From:   Yan Zhao <yan.y.zhao@...el.com>
To:     intel-gfx@...ts.freedesktop.org,
        intel-gvt-dev@...ts.freedesktop.org
Cc:     zhenyuw@...ux.intel.com, zhi.a.wang@...el.com, kvm@...r.kernel.org,
        linux-kernel@...r.kernel.org, Yan Zhao <yan.y.zhao@...el.com>
Subject: [PATCH] drm/i915/gvt: Fix bug in getting msg length in AUX CH registers handler

Msg length should be obtained from value written to AUX_CH_CTL register
rather than from enum type of the register.

Commit 0cad796a2269  ("drm/i915: Use REG_BIT() & co. for AUX CH registers")
incorrectly calculates the msg_length from reg type and yields below
warning in intel_gvt_i2c_handle_aux_ch_write():
"i915 0000:00:02.0: drm_WARN_ON(msg_length != 4)".

Fixes: 0cad796a2269 ("drm/i915: Use REG_BIT() & co. for AUX CH registers")
Signed-off-by: Yan Zhao <yan.y.zhao@...el.com>
---
 drivers/gpu/drm/i915/gvt/edid.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/i915/gvt/edid.c b/drivers/gpu/drm/i915/gvt/edid.c
index 2a0438f12a14..af9afdb53c7f 100644
--- a/drivers/gpu/drm/i915/gvt/edid.c
+++ b/drivers/gpu/drm/i915/gvt/edid.c
@@ -491,7 +491,7 @@ void intel_gvt_i2c_handle_aux_ch_write(struct intel_vgpu *vgpu,
 		return;
 	}
 
-	msg_length = REG_FIELD_GET(DP_AUX_CH_CTL_MESSAGE_SIZE_MASK, reg);
+	msg_length = REG_FIELD_GET(DP_AUX_CH_CTL_MESSAGE_SIZE_MASK, value);
 
 	// check the msg in DATA register.
 	msg = vgpu_vreg(vgpu, offset + 4);
-- 
2.17.1