linux-kernel - Re: [PATCH 10/17] coresight: etr: Track if the device is coherent

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Message-ID: <20171102194022.GC23320@xps15>
Date:   Thu, 2 Nov 2017 13:40:22 -0600
From:   Mathieu Poirier <mathieu.poirier@...aro.org>
To:     Suzuki K Poulose <suzuki.poulose@....com>
Cc:     linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
        rob.walker@....com, mike.leach@...aro.org,
        coresight@...ts.linaro.org
Subject: Re: [PATCH 10/17] coresight: etr: Track if the device is coherent

On Thu, Oct 19, 2017 at 06:15:46PM +0100, Suzuki K Poulose wrote:
> Track if the ETR is dma-coherent or not. This will be useful
> in deciding if we should use software buffering for perf.
> 
> Cc: Mathieu Poirier <mathieu.poirier@...aro.org>
> Signed-off-by: Suzuki K Poulose <suzuki.poulose@....com>
> ---
>  drivers/hwtracing/coresight/coresight-tmc.c | 5 ++++-
>  drivers/hwtracing/coresight/coresight-tmc.h | 1 +
>  2 files changed, 5 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/hwtracing/coresight/coresight-tmc.c b/drivers/hwtracing/coresight/coresight-tmc.c
> index 4939333cc6c7..5a8c41130f96 100644
> --- a/drivers/hwtracing/coresight/coresight-tmc.c
> +++ b/drivers/hwtracing/coresight/coresight-tmc.c
> @@ -347,6 +347,9 @@ static int tmc_etr_setup_caps(struct tmc_drvdata *drvdata,
>  	if (!(devid & TMC_DEVID_NOSCAT))
>  		tmc_etr_set_cap(drvdata, TMC_ETR_SG);
>  
> +	if (device_get_dma_attr(drvdata->dev) == DEV_DMA_COHERENT)
> +		tmc_etr_set_cap(drvdata, TMC_ETR_COHERENT);
> +
>  	/* Check if the AXI address width is available */
>  	if (devid & TMC_DEVID_AXIAW_VALID)
>  		dma_mask = ((devid >> TMC_DEVID_AXIAW_SHIFT) &
> @@ -397,7 +400,7 @@ static int tmc_probe(struct amba_device *adev, const struct amba_id *id)
>  	if (!drvdata)
>  		goto out;
>  
> -	drvdata->dev = &adev->dev;
> +	drvdata->dev = dev;

What is that one for?

>  	dev_set_drvdata(dev, drvdata);
>  
>  	/* Validity for the resource is already checked by the AMBA core */
> diff --git a/drivers/hwtracing/coresight/coresight-tmc.h b/drivers/hwtracing/coresight/coresight-tmc.h
> index 50ebc17c4645..69da0b584a6b 100644
> --- a/drivers/hwtracing/coresight/coresight-tmc.h
> +++ b/drivers/hwtracing/coresight/coresight-tmc.h
> @@ -131,6 +131,7 @@ enum tmc_mem_intf_width {
>   * so we have to rely on PID of the IP to detect the functionality.
>   */
>  #define TMC_ETR_SAVE_RESTORE		(0x1U << 2)
> +#define TMC_ETR_COHERENT		(0x1U << 3)
>  
>  /* Coresight SoC-600 TMC-ETR unadvertised capabilities */
>  #define CORESIGHT_SOC_600_ETR_CAPS	\
> -- 
> 2.13.6
>