[PATCH v6 02/26] coresight: etm4x: Skip accessing TRCPDCR in save/restore

From: Suzuki K Poulose
Date: Thu Jan 07 2021 - 07:40:37 EST


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.poirier@xxxxxxxxxx>
Cc: Mike Leach <mike.leach@xxxxxxxxxx>
Cc: Sai Prakash Ranjan <saiprakash.ranjan@xxxxxxxxxxxxxx>
Cc: Tingwei Zhang <tingwei@xxxxxxxxxxxxxx>
Reviewed-by: Sai Prakash Ranjan <saiprakash.ranjan@xxxxxxxxxxxxxx>
Tested-by: Sai Prakash Ranjan <saiprakash.ranjan@xxxxxxxxxxxxxx>
Signed-off-by: Suzuki K Poulose <suzuki.poulose@xxxxxxx>
---
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