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coresight: etm4x: Skip accessing TRCPDCR in save/restore

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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.

Link: https://lore.kernel.org/r/20210110224850.1880240-3-suzuki.poulose@arm.com
Fixes: 02510a5aa7 ("coresight: etm4x: Add support to skip trace unit power up")
Cc: Mathieu Poirier <mathieu.poirier@linaro.org>
Cc: Mike Leach <mike.leach@linaro.org>
Cc: Sai Prakash Ranjan <saiprakash.ranjan@codeaurora.org>
Cc: Tingwei Zhang <tingwei@codeaurora.org>
Tested-by: Sai Prakash Ranjan <saiprakash.ranjan@codeaurora.org>
Reviewed-by: Sai Prakash Ranjan <saiprakash.ranjan@codeaurora.org>
Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com>
Signed-off-by: Mathieu Poirier <mathieu.poirier@linaro.org>
Link: https://lore.kernel.org/r/20210201181351.1475223-5-mathieu.poirier@linaro.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Suzuki K Poulose 2021-02-01 11:13:24 -07:00 committed by Greg Kroah-Hartman
parent f6a18f354c
commit df81b43802
1 changed files with 7 additions and 5 deletions
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12
drivers/hwtracing/coresight/coresight-etm4x-core.c
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@ -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;