[PATCH] coresight: Fix disabling of CoreSight TPIU

[Mathieu Poirier]

Hi Robert,

On 24 November 2017 at 02:58, Robert Walker <robert.walker at 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 at 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


> --
> 1.9.1
>