Re: [PATCH 08/25] media: atmel: properly get pm_runtime

[<Eugen.Hristev@microchip.com>]

On 5/5/21 3:08 PM, Jonathan Cameron wrote:
> On Wed, 5 May 2021 11:41:58 +0200
> Mauro Carvalho Chehab <mchehab+huawei@kernel.org> wrote:
> 
>> There are several issues in the way the atmel driver handles
>> pm_runtime_get_sync():
>>
>> - it doesn't check return codes;
>> - it doesn't properly decrement the usage_count on all places;
>> - it starts streaming even if pm_runtime_get_sync() fails.
>> - while it tries to get pm_runtime at the clock enable logic,
>>    it doesn't check if the operation was suceeded.
>>
>> Replace all occurrences of it to use the new kAPI:
>> pm_runtime_resume_and_get(), which ensures that, if the
>> return code is not negative, the usage_count was incremented.
>>
>> With that, add additional checks when this is called, in order
>> to ensure that errors will be properly addressed.
>>
>> Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
> 
> Hi Mauro, I don't know media enough to know what is the right answer
> but in some of this series, a failure in
> pm_runtime_resume_and_get() leads to a bunch of buffer cleanup
> (patch 22 being an example) and in others return happens without doing
> that cleanup.
> 
> It might be both are safe, or I'm missing something else, but I'm
> certainly not confident enough to give any tags on this one as a result
> of that mismatch.
> 
>> ---
>>   drivers/media/platform/atmel/atmel-isc-base.c | 30 ++++++++++++++-----
>>   drivers/media/platform/atmel/atmel-isi.c      | 19 +++++++++---
>>   2 files changed, 38 insertions(+), 11 deletions(-)
>>
>> diff --git a/drivers/media/platform/atmel/atmel-isc-base.c b/drivers/media/platform/atmel/atmel-isc-base.c
>> index fe3ec8d0eaee..ce8e1351fa53 100644
>> --- a/drivers/media/platform/atmel/atmel-isc-base.c
>> +++ b/drivers/media/platform/atmel/atmel-isc-base.c
>> @@ -294,9 +294,13 @@ static int isc_wait_clk_stable(struct clk_hw *hw)
>>   static int isc_clk_prepare(struct clk_hw *hw)
>>   {
>>        struct isc_clk *isc_clk = to_isc_clk(hw);
>> +     int ret;
>>
>> -     if (isc_clk->id == ISC_ISPCK)
>> -             pm_runtime_get_sync(isc_clk->dev);
>> +     if (isc_clk->id == ISC_ISPCK) {
>> +             ret = pm_runtime_resume_and_get(isc_clk->dev);
>> +             if (ret < 0)
>> +                     return ret;
>> +     }

Hi Mauro,

With this patch, the ISC is broken on latest media tree. It looks like 
pm_runtime_resume_and_get for the ISC_ISPCK clock returns -ENOACCESS and 
thus, the probe of the driver fails:

atmel-sama5d2-isc f0008000.isc: failed to enable ispck: -13
atmel-sama5d2-isc: probe of f0008000.isc failed with error -13


Could you point out how I could fix this ? Maybe the isc_clk->dev is not 
properly handled/initialized in some other part of the code ?

Thanks !
Eugen


>>
>>        return isc_wait_clk_stable(hw);
>>   }
>> @@ -353,9 +357,13 @@ static int isc_clk_is_enabled(struct clk_hw *hw)
>>   {
>>        struct isc_clk *isc_clk = to_isc_clk(hw);
>>        u32 status;
>> +     int ret;
>>
>> -     if (isc_clk->id == ISC_ISPCK)
>> -             pm_runtime_get_sync(isc_clk->dev);
>> +     if (isc_clk->id == ISC_ISPCK) {
>> +             ret = pm_runtime_resume_and_get(isc_clk->dev);
>> +             if (ret < 0)
>> +                     return 0;
>> +     }
>>
>>        regmap_read(isc_clk->regmap, ISC_CLKSR, &status);
>>
>> @@ -807,7 +815,12 @@ static int isc_start_streaming(struct vb2_queue *vq, unsigned int count)
>>                goto err_start_stream;
>>        }
>>
>> -     pm_runtime_get_sync(isc->dev);
>> +     ret = pm_runtime_resume_and_get(isc->dev);
>> +     if (ret < 0) {
>> +             v4l2_err(&isc->v4l2_dev, "RPM resume failed in subdev %d\n",
>> +                      ret);
>> +             goto err_pm_get;
>> +     }
>>
>>        ret = isc_configure(isc);
>>        if (unlikely(ret))
>> @@ -838,7 +851,7 @@ static int isc_start_streaming(struct vb2_queue *vq, unsigned int count)
>>
>>   err_configure:
>>        pm_runtime_put_sync(isc->dev);
>> -
>> +err_pm_get:
>>        v4l2_subdev_call(isc->current_subdev->sd, video, s_stream, 0);
>>
>>   err_start_stream:
>> @@ -1809,6 +1822,7 @@ static void isc_awb_work(struct work_struct *w)
>>        u32 baysel;
>>        unsigned long flags;
>>        u32 min, max;
>> +     int ret;
>>
>>        /* streaming is not active anymore */
>>        if (isc->stop)
>> @@ -1831,7 +1845,9 @@ static void isc_awb_work(struct work_struct *w)
>>        ctrls->hist_id = hist_id;
>>        baysel = isc->config.sd_format->cfa_baycfg << ISC_HIS_CFG_BAYSEL_SHIFT;
>>
>> -     pm_runtime_get_sync(isc->dev);
>> +     ret = pm_runtime_resume_and_get(isc->dev);
>> +     if (ret < 0)
>> +             return;
>>
>>        /*
>>         * only update if we have all the required histograms and controls
>> diff --git a/drivers/media/platform/atmel/atmel-isi.c b/drivers/media/platform/atmel/atmel-isi.c
>> index e392b3efe363..5b1dd358f2e6 100644
>> --- a/drivers/media/platform/atmel/atmel-isi.c
>> +++ b/drivers/media/platform/atmel/atmel-isi.c
>> @@ -422,7 +422,9 @@ static int start_streaming(struct vb2_queue *vq, unsigned int count)
>>        struct frame_buffer *buf, *node;
>>        int ret;
>>
>> -     pm_runtime_get_sync(isi->dev);
>> +     ret = pm_runtime_resume_and_get(isi->dev);
>> +     if (ret < 0)
>> +             return ret;
> This is the case I'm referring to above.
> 
>>
>>        /* Enable stream on the sub device */
>>        ret = v4l2_subdev_call(isi->entity.subdev, video, s_stream, 1);
>> @@ -782,9 +784,10 @@ static int isi_enum_frameintervals(struct file *file, void *fh,
>>        return 0;
>>   }
>>
>> -static void isi_camera_set_bus_param(struct atmel_isi *isi)
>> +static int isi_camera_set_bus_param(struct atmel_isi *isi)
>>   {
>>        u32 cfg1 = 0;
>> +     int ret;
>>
>>        /* set bus param for ISI */
>>        if (isi->pdata.hsync_act_low)
>> @@ -801,12 +804,16 @@ static void isi_camera_set_bus_param(struct atmel_isi *isi)
>>        cfg1 |= ISI_CFG1_THMASK_BEATS_16;
>>
>>        /* Enable PM and peripheral clock before operate isi registers */
>> -     pm_runtime_get_sync(isi->dev);
>> +     ret = pm_runtime_resume_and_get(isi->dev);
>> +     if (ret < 0)
>> +             return ret;
>>
>>        isi_writel(isi, ISI_CTRL, ISI_CTRL_DIS);
>>        isi_writel(isi, ISI_CFG1, cfg1);
>>
>>        pm_runtime_put(isi->dev);
>> +
>> +     return 0;
>>   }
>>
>>   /* -----------------------------------------------------------------------*/
>> @@ -1085,7 +1092,11 @@ static int isi_graph_notify_complete(struct v4l2_async_notifier *notifier)
>>                dev_err(isi->dev, "No supported mediabus format found\n");
>>                return ret;
>>        }
>> -     isi_camera_set_bus_param(isi);
>> +     ret = isi_camera_set_bus_param(isi);
>> +     if (ret) {
>> +             dev_err(isi->dev, "Can't wake up device\n");
>> +             return ret;
>> +     }
>>
>>        ret = isi_set_default_fmt(isi);
>>        if (ret) {
>