[PATCH v7 02/28] coresight: etm4x: Skip accessing TRCPDCR in save/restore

[Suzuki K Poulose]

When the ETM is affected by Qualcomm errata, modifying the
TRCPDCR could cause the system hang. Even though this is
taken care of during enable/disable ETM, the ETM state
save/restore could still access the TRCPDCR. Make sure
we skip the access during the save/restore.

Found by code inspection.

Fixes: 02510a5aa78df45 ("coresight: etm4x: Add support to skip trace unit power 
up")
Cc: Mathieu Poirier <mathieu.poir...@linaro.org>
Cc: Mike Leach <mike.le...@linaro.org>
Cc: Sai Prakash Ranjan <saiprakash.ran...@codeaurora.org>
Cc: Tingwei Zhang <ting...@codeaurora.org>
Reviewed-by: Sai Prakash Ranjan <saiprakash.ran...@codeaurora.org>
Tested-by: Sai Prakash Ranjan <saiprakash.ran...@codeaurora.org>
Signed-off-by: Suzuki K Poulose <suzuki.poul...@arm.com>
---
 drivers/hwtracing/coresight/coresight-etm4x-core.c | 12 +++++++-----
 1 file changed, 7 insertions(+), 5 deletions(-)

diff --git a/drivers/hwtracing/coresight/coresight-etm4x-core.c 
b/drivers/hwtracing/coresight/coresight-etm4x-core.c
index 76526679b998..cce65fc0c9aa 100644
--- a/drivers/hwtracing/coresight/coresight-etm4x-core.c
+++ b/drivers/hwtracing/coresight/coresight-etm4x-core.c
@@ -1373,7 +1373,8 @@ static int etm4_cpu_save(struct etmv4_drvdata *drvdata)
 
        state->trcclaimset = readl(drvdata->base + TRCCLAIMCLR);
 
-       state->trcpdcr = readl(drvdata->base + TRCPDCR);
+       if (!drvdata->skip_power_up)
+               state->trcpdcr = readl(drvdata->base + TRCPDCR);
 
        /* wait for TRCSTATR.IDLE to go up */
        if (coresight_timeout(drvdata->base, TRCSTATR, TRCSTATR_IDLE_BIT, 1)) {
@@ -1391,9 +1392,9 @@ static int etm4_cpu_save(struct etmv4_drvdata *drvdata)
         * potentially save power on systems that respect the TRCPDCR_PU
         * despite requesting software to save/restore state.
         */
-       writel_relaxed((state->trcpdcr & ~TRCPDCR_PU),
-                       drvdata->base + TRCPDCR);
-
+       if (!drvdata->skip_power_up)
+               writel_relaxed((state->trcpdcr & ~TRCPDCR_PU),
+                               drvdata->base + TRCPDCR);
 out:
        CS_LOCK(drvdata->base);
        return ret;
@@ -1488,7 +1489,8 @@ static void etm4_cpu_restore(struct etmv4_drvdata 
*drvdata)
 
        writel_relaxed(state->trcclaimset, drvdata->base + TRCCLAIMSET);
 
-       writel_relaxed(state->trcpdcr, drvdata->base + TRCPDCR);
+       if (!drvdata->skip_power_up)
+               writel_relaxed(state->trcpdcr, drvdata->base + TRCPDCR);
 
        drvdata->state_needs_restore = false;
 
-- 
2.24.1