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coresight: tmc: Cleanup operation mode handling
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The mode of operation of the TMC tracked in drvdata->mode is defined
as a local_t type. This is always checked and modified under the
drvdata->spinlock and hence we don't need local_t for it and the
unnecessary synchronisation instructions that comes with it. This
change makes the code a bit more cleaner.

Also fixes the order in which we update the drvdata->mode to
CS_MODE_DISABLED. i.e, in tmc_disable_etX_sink we change the
mode to CS_MODE_DISABLED before invoking tmc_disable_etX_hw()
which in turn depends on the mode to decide whether to dump the
trace to a buffer.

Applies on mathieu's coresight/next tree [1]

https://git.linaro.org/kernel/coresight.git next

Reported-by: Venkatesh Vivekanandan <[email protected]>
Cc: Mathieu Poirier <[email protected]>
Signed-off-by: Suzuki K Poulose <[email protected]>
Signed-off-by: Mathieu Poirier <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>
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@gregkh
Suzuki K. Poulose authored and gregkh committed Nov 29, 2016
1 parent d52c975 commit 297ab90
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Showing 3 changed files with 26 additions and 34 deletions.
32 changes: 14 additions & 18 deletions drivers/hwtracing/coresight/coresight-tmc-etf.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -70,7 +70,7 @@ static void tmc_etb_disable_hw(struct tmc_drvdata *drvdata)
* When operating in sysFS mode the content of the buffer needs to be
* read before the TMC is disabled.
*/
if (local_read(&drvdata->mode) == CS_MODE_SYSFS)
if (drvdata->mode == CS_MODE_SYSFS)
tmc_etb_dump_hw(drvdata);
tmc_disable_hw(drvdata);

Expand Down Expand Up @@ -108,7 +108,6 @@ static int tmc_enable_etf_sink_sysfs(struct coresight_device *csdev, u32 mode)
int ret = 0;
bool used = false;
char *buf = NULL;
long val;
unsigned long flags;
struct tmc_drvdata *drvdata = dev_get_drvdata(csdev->dev.parent);

Expand Down Expand Up @@ -138,13 +137,12 @@ static int tmc_enable_etf_sink_sysfs(struct coresight_device *csdev, u32 mode)
goto out;
}

val = local_xchg(&drvdata->mode, mode);
/*
* In sysFS mode we can have multiple writers per sink. Since this
* sink is already enabled no memory is needed and the HW need not be
* touched.
*/
if (val == CS_MODE_SYSFS)
if (drvdata->mode == CS_MODE_SYSFS)
goto out;

/*
Expand All @@ -163,6 +161,7 @@ static int tmc_enable_etf_sink_sysfs(struct coresight_device *csdev, u32 mode)
drvdata->buf = buf;
}

drvdata->mode = CS_MODE_SYSFS;
tmc_etb_enable_hw(drvdata);
out:
spin_unlock_irqrestore(&drvdata->spinlock, flags);
Expand All @@ -180,7 +179,6 @@ static int tmc_enable_etf_sink_sysfs(struct coresight_device *csdev, u32 mode)
static int tmc_enable_etf_sink_perf(struct coresight_device *csdev, u32 mode)
{
int ret = 0;
long val;
unsigned long flags;
struct tmc_drvdata *drvdata = dev_get_drvdata(csdev->dev.parent);

Expand All @@ -194,17 +192,17 @@ static int tmc_enable_etf_sink_perf(struct coresight_device *csdev, u32 mode)
goto out;
}

val = local_xchg(&drvdata->mode, mode);
/*
* In Perf mode there can be only one writer per sink. There
* is also no need to continue if the ETB/ETR is already operated
* from sysFS.
*/
if (val != CS_MODE_DISABLED) {
if (drvdata->mode != CS_MODE_DISABLED) {
ret = -EINVAL;
goto out;
}

drvdata->mode = mode;
tmc_etb_enable_hw(drvdata);
out:
spin_unlock_irqrestore(&drvdata->spinlock, flags);
Expand All @@ -227,7 +225,6 @@ static int tmc_enable_etf_sink(struct coresight_device *csdev, u32 mode)

static void tmc_disable_etf_sink(struct coresight_device *csdev)
{
long val;
unsigned long flags;
struct tmc_drvdata *drvdata = dev_get_drvdata(csdev->dev.parent);

Expand All @@ -237,10 +234,11 @@ static void tmc_disable_etf_sink(struct coresight_device *csdev)
return;
}

val = local_xchg(&drvdata->mode, CS_MODE_DISABLED);
/* Disable the TMC only if it needs to */
if (val != CS_MODE_DISABLED)
if (drvdata->mode != CS_MODE_DISABLED) {
tmc_etb_disable_hw(drvdata);
drvdata->mode = CS_MODE_DISABLED;
}

spin_unlock_irqrestore(&drvdata->spinlock, flags);

Expand All @@ -260,7 +258,7 @@ static int tmc_enable_etf_link(struct coresight_device *csdev,
}

tmc_etf_enable_hw(drvdata);
local_set(&drvdata->mode, CS_MODE_SYSFS);
drvdata->mode = CS_MODE_SYSFS;
spin_unlock_irqrestore(&drvdata->spinlock, flags);

dev_info(drvdata->dev, "TMC-ETF enabled\n");
Expand All @@ -280,7 +278,7 @@ static void tmc_disable_etf_link(struct coresight_device *csdev,
}

tmc_etf_disable_hw(drvdata);
local_set(&drvdata->mode, CS_MODE_DISABLED);
drvdata->mode = CS_MODE_DISABLED;
spin_unlock_irqrestore(&drvdata->spinlock, flags);

dev_info(drvdata->dev, "TMC disabled\n");
Expand Down Expand Up @@ -383,7 +381,7 @@ static void tmc_update_etf_buffer(struct coresight_device *csdev,
return;

/* This shouldn't happen */
if (WARN_ON_ONCE(local_read(&drvdata->mode) != CS_MODE_PERF))
if (WARN_ON_ONCE(drvdata->mode != CS_MODE_PERF))
return;

CS_UNLOCK(drvdata->base);
Expand Down Expand Up @@ -504,7 +502,6 @@ const struct coresight_ops tmc_etf_cs_ops = {

int tmc_read_prepare_etb(struct tmc_drvdata *drvdata)
{
long val;
enum tmc_mode mode;
int ret = 0;
unsigned long flags;
Expand All @@ -528,9 +525,8 @@ int tmc_read_prepare_etb(struct tmc_drvdata *drvdata)
goto out;
}

val = local_read(&drvdata->mode);
/* Don't interfere if operated from Perf */
if (val == CS_MODE_PERF) {
if (drvdata->mode == CS_MODE_PERF) {
ret = -EINVAL;
goto out;
}
Expand All @@ -542,7 +538,7 @@ int tmc_read_prepare_etb(struct tmc_drvdata *drvdata)
}

/* Disable the TMC if need be */
if (val == CS_MODE_SYSFS)
if (drvdata->mode == CS_MODE_SYSFS)
tmc_etb_disable_hw(drvdata);

drvdata->reading = true;
Expand Down Expand Up @@ -573,7 +569,7 @@ int tmc_read_unprepare_etb(struct tmc_drvdata *drvdata)
}

/* Re-enable the TMC if need be */
if (local_read(&drvdata->mode) == CS_MODE_SYSFS) {
if (drvdata->mode == CS_MODE_SYSFS) {
/*
* The trace run will continue with the same allocated trace
* buffer. As such zero-out the buffer so that we don't end
Expand Down
26 changes: 11 additions & 15 deletions drivers/hwtracing/coresight/coresight-tmc-etr.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -86,7 +86,7 @@ static void tmc_etr_disable_hw(struct tmc_drvdata *drvdata)
* When operating in sysFS mode the content of the buffer needs to be
* read before the TMC is disabled.
*/
if (local_read(&drvdata->mode) == CS_MODE_SYSFS)
if (drvdata->mode == CS_MODE_SYSFS)
tmc_etr_dump_hw(drvdata);
tmc_disable_hw(drvdata);

Expand All @@ -97,7 +97,6 @@ static int tmc_enable_etr_sink_sysfs(struct coresight_device *csdev, u32 mode)
{
int ret = 0;
bool used = false;
long val;
unsigned long flags;
void __iomem *vaddr = NULL;
dma_addr_t paddr;
Expand Down Expand Up @@ -134,13 +133,12 @@ static int tmc_enable_etr_sink_sysfs(struct coresight_device *csdev, u32 mode)
goto out;
}

val = local_xchg(&drvdata->mode, mode);
/*
* In sysFS mode we can have multiple writers per sink. Since this
* sink is already enabled no memory is needed and the HW need not be
* touched.
*/
if (val == CS_MODE_SYSFS)
if (drvdata->mode == CS_MODE_SYSFS)
goto out;

/*
Expand All @@ -157,6 +155,7 @@ static int tmc_enable_etr_sink_sysfs(struct coresight_device *csdev, u32 mode)

memset(drvdata->vaddr, 0, drvdata->size);

drvdata->mode = CS_MODE_SYSFS;
tmc_etr_enable_hw(drvdata);
out:
spin_unlock_irqrestore(&drvdata->spinlock, flags);
Expand All @@ -174,7 +173,6 @@ static int tmc_enable_etr_sink_sysfs(struct coresight_device *csdev, u32 mode)
static int tmc_enable_etr_sink_perf(struct coresight_device *csdev, u32 mode)
{
int ret = 0;
long val;
unsigned long flags;
struct tmc_drvdata *drvdata = dev_get_drvdata(csdev->dev.parent);

Expand All @@ -188,17 +186,17 @@ static int tmc_enable_etr_sink_perf(struct coresight_device *csdev, u32 mode)
goto out;
}

val = local_xchg(&drvdata->mode, mode);
/*
* In Perf mode there can be only one writer per sink. There
* is also no need to continue if the ETR is already operated
* from sysFS.
*/
if (val != CS_MODE_DISABLED) {
if (drvdata->mode != CS_MODE_DISABLED) {
ret = -EINVAL;
goto out;
}

drvdata->mode = CS_MODE_PERF;
tmc_etr_enable_hw(drvdata);
out:
spin_unlock_irqrestore(&drvdata->spinlock, flags);
Expand All @@ -221,7 +219,6 @@ static int tmc_enable_etr_sink(struct coresight_device *csdev, u32 mode)

static void tmc_disable_etr_sink(struct coresight_device *csdev)
{
long val;
unsigned long flags;
struct tmc_drvdata *drvdata = dev_get_drvdata(csdev->dev.parent);

Expand All @@ -231,10 +228,11 @@ static void tmc_disable_etr_sink(struct coresight_device *csdev)
return;
}

val = local_xchg(&drvdata->mode, CS_MODE_DISABLED);
/* Disable the TMC only if it needs to */
if (val != CS_MODE_DISABLED)
if (drvdata->mode != CS_MODE_DISABLED) {
tmc_etr_disable_hw(drvdata);
drvdata->mode = CS_MODE_DISABLED;
}

spin_unlock_irqrestore(&drvdata->spinlock, flags);

Expand All @@ -253,7 +251,6 @@ const struct coresight_ops tmc_etr_cs_ops = {
int tmc_read_prepare_etr(struct tmc_drvdata *drvdata)
{
int ret = 0;
long val;
unsigned long flags;

/* config types are set a boot time and never change */
Expand All @@ -266,9 +263,8 @@ int tmc_read_prepare_etr(struct tmc_drvdata *drvdata)
goto out;
}

val = local_read(&drvdata->mode);
/* Don't interfere if operated from Perf */
if (val == CS_MODE_PERF) {
if (drvdata->mode == CS_MODE_PERF) {
ret = -EINVAL;
goto out;
}
Expand All @@ -280,7 +276,7 @@ int tmc_read_prepare_etr(struct tmc_drvdata *drvdata)
}

/* Disable the TMC if need be */
if (val == CS_MODE_SYSFS)
if (drvdata->mode == CS_MODE_SYSFS)
tmc_etr_disable_hw(drvdata);

drvdata->reading = true;
Expand All @@ -303,7 +299,7 @@ int tmc_read_unprepare_etr(struct tmc_drvdata *drvdata)
spin_lock_irqsave(&drvdata->spinlock, flags);

/* RE-enable the TMC if need be */
if (local_read(&drvdata->mode) == CS_MODE_SYSFS) {
if (drvdata->mode == CS_MODE_SYSFS) {
/*
* The trace run will continue with the same allocated trace
* buffer. The trace buffer is cleared in tmc_etr_enable_hw(),
Expand Down
2 changes: 1 addition & 1 deletion drivers/hwtracing/coresight/coresight-tmc.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -117,7 +117,7 @@ struct tmc_drvdata {
void __iomem *vaddr;
u32 size;
u32 len;
local_t mode;
u32 mode;
enum tmc_config_type config_type;
enum tmc_mem_intf_width memwidth;
u32 trigger_cntr;
Expand Down

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