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coresight: etm4x: Add necessary synchronization for sysreg access

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As per the specification any update to the TRCPRGCTLR must be synchronized
by a context synchronization event (in our case an explicist ISB) before
the TRCSTATR is checked.

Link: https://lore.kernel.org/r/20210110224850.1880240-22-suzuki.poulose@arm.com
Cc: Mike Leach <mike.leach@linaro.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/20210201181351.1475223-24-mathieu.poirier@linaro.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Suzuki K Poulose 2021-02-01 11:13:43 -07:00 committed by Greg Kroah-Hartman
parent 4211bfce1e
commit 1ab3bb9df5
1 changed files with 13 additions and 0 deletions
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13
drivers/hwtracing/coresight/coresight-etm4x-core.c
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@ -284,6 +284,15 @@ static int etm4_enable_hw(struct etmv4_drvdata *drvdata)
/* Disable the trace unit before programming trace registers */
etm4x_relaxed_write32(csa, 0, TRCPRGCTLR);
/*
* If we use system instructions, we need to synchronize the
* write to the TRCPRGCTLR, before accessing the TRCSTATR.
* See ARM IHI0064F, section
* "4.3.7 Synchronization of register updates"
*/
if (!csa->io_mem)
isb();
/* wait for TRCSTATR.IDLE to go up */
if (coresight_timeout(csa, TRCSTATR, TRCSTATR_IDLE_BIT, 1))
dev_err(etm_dev,
@ -362,6 +371,10 @@ static int etm4_enable_hw(struct etmv4_drvdata *drvdata)
/* Enable the trace unit */
etm4x_relaxed_write32(csa, 1, TRCPRGCTLR);
/* Synchronize the register updates for sysreg access */
if (!csa->io_mem)
isb();
/* wait for TRCSTATR.IDLE to go back down to '0' */
if (coresight_timeout(csa, TRCSTATR, TRCSTATR_IDLE_BIT, 0))
dev_err(etm_dev,