linux-kernel - [PATCH v2] coresight: etm4x: Fix width of CCITMIN field

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Message-Id: <20231101115206.70810-1-james.clark@arm.com>
Date:   Wed,  1 Nov 2023 11:52:06 +0000
From:   James Clark <james.clark@....com>
To:     coresight@...ts.linaro.org, suzuki.poulose@....com,
        anshuman.khandual@....com, mike.leach@...aro.org
Cc:     James Clark <james.clark@....com>, stable@...r.kernel.org,
        Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
        Pratik Patel <pratikp@...eaurora.org>,
        Mathieu Poirier <mathieu.poirier@...aro.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Kaixu Xia <xiakaixu@...wei.com>,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: [PATCH v2] coresight: etm4x: Fix width of CCITMIN field

CCITMIN is a 12 bit field and doesn't fit in a u8, so extend it to u16.
This probably wasn't an issue previously because values higher than 255
never occurred.

But since commit 0f55b43dedcd ("coresight: etm: Override TRCIDR3.CCITMIN
on errata affected cpus"), a comparison with 256 was done to enable the
errata, generating the following W=1 build error:

  coresight-etm4x-core.c:1188:24: error: result of comparison of
  constant 256 with expression of type 'u8' (aka 'unsigned char') is
  always false [-Werror,-Wtautological-constant-out-of-range-compare]

   if (drvdata->ccitmin == 256)

Cc: stable@...r.kernel.org
Fixes: 2e1cdfe184b5 ("coresight-etm4x: Adding CoreSight ETM4x driver")
Reviewed-by: Mike Leach <mike.leach@...aro.org>
Signed-off-by: James Clark <james.clark@....com>
---

Changes since V1:
  * Change the fixes commit to the original addition of ccitmin, rather
    than the last refactor of the struct.

 drivers/hwtracing/coresight/coresight-etm4x.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/hwtracing/coresight/coresight-etm4x.h b/drivers/hwtracing/coresight/coresight-etm4x.h
index 20e2e4cb7614..da17b6c49b0f 100644
--- a/drivers/hwtracing/coresight/coresight-etm4x.h
+++ b/drivers/hwtracing/coresight/coresight-etm4x.h
@@ -1036,7 +1036,7 @@ struct etmv4_drvdata {
 	u8				ctxid_size;
 	u8				vmid_size;
 	u8				ccsize;
-	u8				ccitmin;
+	u16				ccitmin;
 	u8				s_ex_level;
 	u8				ns_ex_level;
 	u8				q_support;
-- 
2.34.1