Hi Mathieu,
-----Original Message----- From: Mathieu Poirier [mailto:mathieu.poirier@linaro.org] Sent: 27 November 2017 17:30 To: Robert Walker Robert.Walker@arm.com Cc: linux-arm-kernel@lists.infradead.org; CoreSight@lists.linaro.org Subject: Re: [PATCH] coresight: Fix disabling of CoreSight TPIU
Hi Robert,
On 24 November 2017 at 02:58, Robert Walker robert.walker@arm.com wrote:
The CoreSight TPIU should be disabled when tracing to other sinks to allow them to operate at full bandwidth.
This patch fixes tpiu_disable_hw() to correctly disable the TPIU by configuring the TPIU to stop on flush, initiating a manual flush, waiting for the flush to complete and then waits for the TPIU to indicate it has stopped.
Signed-off-by: Robert Walker robert.walker@arm.com
drivers/hwtracing/coresight/coresight-tpiu.c | 13 ++++++++++--- 1 file changed, 10 insertions(+), 3 deletions(-)
diff --git a/drivers/hwtracing/coresight/coresight-tpiu.c b/drivers/hwtracing/coresight/coresight-tpiu.c index bef49a3..4b46c49 100644 --- a/drivers/hwtracing/coresight/coresight-tpiu.c +++ b/drivers/hwtracing/coresight/coresight-tpiu.c @@ -46,8 +46,11 @@ #define TPIU_ITATBCTR0 0xef8
/** register definition **/ +/* FFSR - 0x300 */ +#define FFSR_FT_STOPPED BIT(1) /* FFCR - 0x304 */ #define FFCR_FON_MAN BIT(6) +#define FFCR_STOP_FI BIT(12)
/**
- @base: memory mapped base address for this component.
@@ -85,10 +88,14 @@ static void tpiu_disable_hw(struct tpiu_drvdata *drvdata) { CS_UNLOCK(drvdata->base);
/* Clear formatter controle reg. */writel_relaxed(0x0, drvdata->base + TPIU_FFCR);
/* Clear formatter and stop on flush */writel_relaxed(FFCR_STOP_FI, drvdata->base + TPIU_FFCR); /* Generate manual flush */
writel_relaxed(FFCR_FON_MAN, drvdata->base + TPIU_FFCR);
writel_relaxed(FFCR_STOP_FI | FFCR_FON_MAN, drvdata->base +TPIU_FFCR);
/* Wait for flush to complete */coresight_timeout(drvdata->base, TPIU_FFCR, FFCR_FON_MAN, 0);/* Wait for formatter to stop */coresight_timeout(drvdata->base, TPIU_FFSR, FFSR_FT_STOPPED,1);
CS_LOCK(drvdata->base);}
Shouldn't we also do this at boot time when the TPIU in _probed() ? That way the TPIU doesn't have to explicitly be enabled and disabled prior to running other tracing sessions.
Thanks, Mathieu
There already is a call to tpiu_disable_hw() in tpiu_probe(), so the TPIU is disabled on boot. When tracing to another sink (e.g. ETR), the TPIU won't be enabled / disabled (i.e. tpiu_enable_hw() and tpiu_disable_hw() won't be called) as it's not on the direct path from source to sink.
Regards
Rob
-- 1.9.1