diff mbox series

remoteproc/mtk_scp: Move clk ops outside send_lock

Message ID 20230104083110.736377-1-wenst@chromium.org
State New
Headers
Series remoteproc/mtk_scp: Move clk ops outside send_lock |

Commit Message

Chen-Yu Tsai Jan. 4, 2023, 8:31 a.m. UTC 
  Clocks are properly reference counted and do not need to be inside the
lock range.

Right now this triggers a false-positive lockdep warning on MT8192 based
Chromebooks, through a combination of mtk-scp that has a cros-ec-rpmsg
sub-device, the (actual) cros-ec I2C adapter registration, I2C client
(not on cros-ec) probe doing i2c transfers and enabling clocks.

This is a false positive because the cros-ec-rpmsg under mtk-scp does
not have an I2C adapter, and also each I2C adapter and cros-ec instance
have their own mutex.

Move the clk operations outside of the send_lock range.

Fixes: ("63c13d61eafe remoteproc/mediatek: add SCP support for mt8183")
Signed-off-by: Chen-Yu Tsai <wenst@chromium.org>
---
 drivers/remoteproc/mtk_scp_ipi.c | 11 +++++------
 1 file changed, 5 insertions(+), 6 deletions(-)

Comments

AngeloGioacchino Del Regno Jan. 4, 2023, 9:23 a.m. UTC | #1 
Il 04/01/23 09:31, Chen-Yu Tsai ha scritto:
> Clocks are properly reference counted and do not need to be inside the
> lock range.
> 
> Right now this triggers a false-positive lockdep warning on MT8192 based
> Chromebooks, through a combination of mtk-scp that has a cros-ec-rpmsg
> sub-device, the (actual) cros-ec I2C adapter registration, I2C client
> (not on cros-ec) probe doing i2c transfers and enabling clocks.
> 
> This is a false positive because the cros-ec-rpmsg under mtk-scp does
> not have an I2C adapter, and also each I2C adapter and cros-ec instance
> have their own mutex.
> 
> Move the clk operations outside of the send_lock range.
> 
> Fixes: ("63c13d61eafe remoteproc/mediatek: add SCP support for mt8183")
> Signed-off-by: Chen-Yu Tsai <wenst@chromium.org>

Nice catch.

Reviewed-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
Mathieu Poirier Jan. 4, 2023, 10:22 p.m. UTC | #2 
On Wed, Jan 04, 2023 at 04:31:10PM +0800, Chen-Yu Tsai wrote:
> Clocks are properly reference counted and do not need to be inside the
> lock range.
> 
> Right now this triggers a false-positive lockdep warning on MT8192 based
> Chromebooks, through a combination of mtk-scp that has a cros-ec-rpmsg
> sub-device, the (actual) cros-ec I2C adapter registration, I2C client
> (not on cros-ec) probe doing i2c transfers and enabling clocks.
> 
> This is a false positive because the cros-ec-rpmsg under mtk-scp does
> not have an I2C adapter, and also each I2C adapter and cros-ec instance
> have their own mutex.
> 
> Move the clk operations outside of the send_lock range.

Thanks for providing such a clear explanation - it makes my job a lot easier.

> 
> Fixes: ("63c13d61eafe remoteproc/mediatek: add SCP support for mt8183")

This is the wrong format for a "Fixes:" tag.  Please see
Documentation/process/submitting-patches.rst for details.

> Signed-off-by: Chen-Yu Tsai <wenst@chromium.org>

I have fixed the above and applied this patch.

Thanks,
Mathieu

> ---
>  drivers/remoteproc/mtk_scp_ipi.c | 11 +++++------
>  1 file changed, 5 insertions(+), 6 deletions(-)
> 
> diff --git a/drivers/remoteproc/mtk_scp_ipi.c b/drivers/remoteproc/mtk_scp_ipi.c
> index 00f041ebcde6..4c0d121c2f54 100644
> --- a/drivers/remoteproc/mtk_scp_ipi.c
> +++ b/drivers/remoteproc/mtk_scp_ipi.c
> @@ -164,21 +164,21 @@ int scp_ipi_send(struct mtk_scp *scp, u32 id, void *buf, unsigned int len,
>  	    WARN_ON(len > sizeof(send_obj->share_buf)) || WARN_ON(!buf))
>  		return -EINVAL;
>  
> -	mutex_lock(&scp->send_lock);
> -
>  	ret = clk_prepare_enable(scp->clk);
>  	if (ret) {
>  		dev_err(scp->dev, "failed to enable clock\n");
> -		goto unlock_mutex;
> +		return ret;
>  	}
>  
> +	mutex_lock(&scp->send_lock);
> +
>  	 /* Wait until SCP receives the last command */
>  	timeout = jiffies + msecs_to_jiffies(2000);
>  	do {
>  		if (time_after(jiffies, timeout)) {
>  			dev_err(scp->dev, "%s: IPI timeout!\n", __func__);
>  			ret = -ETIMEDOUT;
> -			goto clock_disable;
> +			goto unlock_mutex;
>  		}
>  	} while (readl(scp->reg_base + scp->data->host_to_scp_reg));
>  
> @@ -205,10 +205,9 @@ int scp_ipi_send(struct mtk_scp *scp, u32 id, void *buf, unsigned int len,
>  			ret = 0;
>  	}
>  
> -clock_disable:
> -	clk_disable_unprepare(scp->clk);
>  unlock_mutex:
>  	mutex_unlock(&scp->send_lock);
> +	clk_disable_unprepare(scp->clk);
>  
>  	return ret;
>  }
> -- 
> 2.39.0.314.g84b9a713c41-goog
>
Chen-Yu Tsai Jan. 5, 2023, 3 a.m. UTC | #3 
On Thu, Jan 5, 2023 at 6:22 AM Mathieu Poirier
<mathieu.poirier@linaro.org> wrote:
>
> On Wed, Jan 04, 2023 at 04:31:10PM +0800, Chen-Yu Tsai wrote:
> > Clocks are properly reference counted and do not need to be inside the
> > lock range.
> >
> > Right now this triggers a false-positive lockdep warning on MT8192 based
> > Chromebooks, through a combination of mtk-scp that has a cros-ec-rpmsg
> > sub-device, the (actual) cros-ec I2C adapter registration, I2C client
> > (not on cros-ec) probe doing i2c transfers and enabling clocks.
> >
> > This is a false positive because the cros-ec-rpmsg under mtk-scp does
> > not have an I2C adapter, and also each I2C adapter and cros-ec instance
> > have their own mutex.
> >
> > Move the clk operations outside of the send_lock range.
>
> Thanks for providing such a clear explanation - it makes my job a lot easier.
>
> >
> > Fixes: ("63c13d61eafe remoteproc/mediatek: add SCP support for mt8183")
>
> This is the wrong format for a "Fixes:" tag.  Please see
> Documentation/process/submitting-patches.rst for details.
>
> > Signed-off-by: Chen-Yu Tsai <wenst@chromium.org>
>
> I have fixed the above and applied this patch.

Thanks, and sorry about the brain fart on my end.

ChenYu
Chen-Yu Tsai Jan. 5, 2023, 9:03 a.m. UTC | #4 
On Wed, Jan 4, 2023 at 4:31 PM Chen-Yu Tsai <wenst@chromium.org> wrote:
>
> Clocks are properly reference counted and do not need to be inside the
> lock range.
>
> Right now this triggers a false-positive lockdep warning on MT8192 based
> Chromebooks, through a combination of mtk-scp that has a cros-ec-rpmsg
> sub-device, the (actual) cros-ec I2C adapter registration, I2C client
> (not on cros-ec) probe doing i2c transfers and enabling clocks.
>
> This is a false positive because the cros-ec-rpmsg under mtk-scp does
> not have an I2C adapter, and also each I2C adapter and cros-ec instance
> have their own mutex.
>
> Move the clk operations outside of the send_lock range.

Well this managed to untangle the lockdep warning a bit, but it still
appears. I'll keep looking into it.
diff mbox series

Patch

diff --git a/drivers/remoteproc/mtk_scp_ipi.c b/drivers/remoteproc/mtk_scp_ipi.c
index 00f041ebcde6..4c0d121c2f54 100644
--- a/drivers/remoteproc/mtk_scp_ipi.c
+++ b/drivers/remoteproc/mtk_scp_ipi.c
@@ -164,21 +164,21 @@  int scp_ipi_send(struct mtk_scp *scp, u32 id, void *buf, unsigned int len,
 	    WARN_ON(len > sizeof(send_obj->share_buf)) || WARN_ON(!buf))
 		return -EINVAL;
 
-	mutex_lock(&scp->send_lock);
-
 	ret = clk_prepare_enable(scp->clk);
 	if (ret) {
 		dev_err(scp->dev, "failed to enable clock\n");
-		goto unlock_mutex;
+		return ret;
 	}
 
+	mutex_lock(&scp->send_lock);
+
 	 /* Wait until SCP receives the last command */
 	timeout = jiffies + msecs_to_jiffies(2000);
 	do {
 		if (time_after(jiffies, timeout)) {
 			dev_err(scp->dev, "%s: IPI timeout!\n", __func__);
 			ret = -ETIMEDOUT;
-			goto clock_disable;
+			goto unlock_mutex;
 		}
 	} while (readl(scp->reg_base + scp->data->host_to_scp_reg));
 
@@ -205,10 +205,9 @@  int scp_ipi_send(struct mtk_scp *scp, u32 id, void *buf, unsigned int len,
 			ret = 0;
 	}
 
-clock_disable:
-	clk_disable_unprepare(scp->clk);
 unlock_mutex:
 	mutex_unlock(&scp->send_lock);
+	clk_disable_unprepare(scp->clk);
 
 	return ret;
 }