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| author | Suzuki K Poulose <suzuki.poulose@arm.com> | 2021-02-01 11:13:43 -0700 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2021-02-04 17:00:34 +0100 |
| commit | 1ab3bb9df5e35183fee8da2b3fb30feda9a53ce9 (patch) | |
| tree | d1193b15fa25ab779f3c61b1f71db16db93f7131 /drivers/hwtracing | |
| parent | 4211bfce1eb9962f2ae1972837c032ad6d48f292 (diff) | |
| download | lwn-1ab3bb9df5e35183fee8da2b3fb30feda9a53ce9.tar.gz lwn-1ab3bb9df5e35183fee8da2b3fb30feda9a53ce9.zip | |
coresight: etm4x: Add necessary synchronization for sysreg access
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>
Diffstat (limited to 'drivers/hwtracing')
| -rw-r--r-- | drivers/hwtracing/coresight/coresight-etm4x-core.c | 13 |
1 files changed, 13 insertions, 0 deletions
diff --git a/drivers/hwtracing/coresight/coresight-etm4x-core.c b/drivers/hwtracing/coresight/coresight-etm4x-core.c index a09a653fc5b0..8d644e93de51 100644 --- a/drivers/hwtracing/coresight/coresight-etm4x-core.c +++ b/drivers/hwtracing/coresight/coresight-etm4x-core.c @@ -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, |