media: rcar_drif: Use dma_request_chan() instead dma_request_slave_channel()
diff mbox series

Message ID 20191217104025.23318-1-peter.ujfalusi@ti.com
State New
Headers show
Series
  • media: rcar_drif: Use dma_request_chan() instead dma_request_slave_channel()
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Commit Message

Peter Ujfalusi Dec. 17, 2019, 10:40 a.m. UTC
dma_request_slave_channel() is a wrapper on top of dma_request_chan()
eating up the error code.

By using dma_request_chan() directly the driver can support deferred
probing against DMA.

Signed-off-by: Peter Ujfalusi <peter.ujfalusi@ti.com>
---
 drivers/media/platform/rcar_drif.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

Comments

Geert Uytterhoeven Jan. 20, 2020, 12:05 p.m. UTC | #1
On Tue, Dec 17, 2019 at 11:41 AM Peter Ujfalusi <peter.ujfalusi@ti.com> wrote:
> dma_request_slave_channel() is a wrapper on top of dma_request_chan()
> eating up the error code.
>
> By using dma_request_chan() directly the driver can support deferred
> probing against DMA.
>
> Signed-off-by: Peter Ujfalusi <peter.ujfalusi@ti.com>

Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>

One comment below.

> --- a/drivers/media/platform/rcar_drif.c
> +++ b/drivers/media/platform/rcar_drif.c
> @@ -275,10 +275,10 @@ static int rcar_drif_alloc_dmachannels(struct rcar_drif_sdr *sdr)
>         for_each_rcar_drif_channel(i, &sdr->cur_ch_mask) {
>                 struct rcar_drif *ch = sdr->ch[i];
>
> -               ch->dmach = dma_request_slave_channel(&ch->pdev->dev, "rx");
> -               if (!ch->dmach) {
> +               ch->dmach = dma_request_chan(&ch->pdev->dev, "rx");
> +               if (IS_ERR(ch->dmach)) {
>                         rdrif_err(sdr, "ch%u: dma channel req failed\n", i);

Now there is an error code, you might (1) want to print it, and (2) only
do so when it is not due to probe deferral:

        if (PTR_ERR(ch->dmach) != -EPROBE_DEFER)
                rdrif_err(sdr, "ch%u: dma channel req failed %pe\n",
i, ch->dmach);

> -                       ret = -ENODEV;
> +                       ret = PTR_ERR(ch->dmach);
>                         goto dmach_error;
>                 }

Gr{oetje,eeting}s,

                        Geert
Peter Ujfalusi Jan. 20, 2020, 12:10 p.m. UTC | #2
Hi Geert,

On 20/01/2020 14.05, Geert Uytterhoeven wrote:
> On Tue, Dec 17, 2019 at 11:41 AM Peter Ujfalusi <peter.ujfalusi@ti.com> wrote:
>> dma_request_slave_channel() is a wrapper on top of dma_request_chan()
>> eating up the error code.
>>
>> By using dma_request_chan() directly the driver can support deferred
>> probing against DMA.
>>
>> Signed-off-by: Peter Ujfalusi <peter.ujfalusi@ti.com>
> 
> Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>
> 
> One comment below.
> 
>> --- a/drivers/media/platform/rcar_drif.c
>> +++ b/drivers/media/platform/rcar_drif.c
>> @@ -275,10 +275,10 @@ static int rcar_drif_alloc_dmachannels(struct rcar_drif_sdr *sdr)
>>         for_each_rcar_drif_channel(i, &sdr->cur_ch_mask) {
>>                 struct rcar_drif *ch = sdr->ch[i];
>>
>> -               ch->dmach = dma_request_slave_channel(&ch->pdev->dev, "rx");
>> -               if (!ch->dmach) {
>> +               ch->dmach = dma_request_chan(&ch->pdev->dev, "rx");
>> +               if (IS_ERR(ch->dmach)) {
>>                         rdrif_err(sdr, "ch%u: dma channel req failed\n", i);
> 
> Now there is an error code, you might (1) want to print it, and (2) only
> do so when it is not due to probe deferral:
> 
>         if (PTR_ERR(ch->dmach) != -EPROBE_DEFER)
>                 rdrif_err(sdr, "ch%u: dma channel req failed %pe\n",
> i, ch->dmach);

Yes, this is true.

> 
>> -                       ret = -ENODEV;
>> +                       ret = PTR_ERR(ch->dmach);

if (ret != -EPROBE_DEFER)
	rdrif_err(sdr, "ch%u: dma channel req failed (%d)\n", i, ret);

might be simpler.

>>                         goto dmach_error;
>>                 }
> 
> Gr{oetje,eeting}s,
> 
>                         Geert
> 

- Péter

Texas Instruments Finland Oy, Porkkalankatu 22, 00180 Helsinki.
Y-tunnus/Business ID: 0615521-4. Kotipaikka/Domicile: Helsinki
Geert Uytterhoeven Jan. 20, 2020, 12:36 p.m. UTC | #3
Hi Peter,

On Mon, Jan 20, 2020 at 1:09 PM Peter Ujfalusi <peter.ujfalusi@ti.com> wrote:
> On 20/01/2020 14.05, Geert Uytterhoeven wrote:
> > On Tue, Dec 17, 2019 at 11:41 AM Peter Ujfalusi <peter.ujfalusi@ti.com> wrote:
> >> dma_request_slave_channel() is a wrapper on top of dma_request_chan()
> >> eating up the error code.
> >>
> >> By using dma_request_chan() directly the driver can support deferred
> >> probing against DMA.
> >>
> >> Signed-off-by: Peter Ujfalusi <peter.ujfalusi@ti.com>
> >
> > Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>
> >
> > One comment below.
> >
> >> --- a/drivers/media/platform/rcar_drif.c
> >> +++ b/drivers/media/platform/rcar_drif.c
> >> @@ -275,10 +275,10 @@ static int rcar_drif_alloc_dmachannels(struct rcar_drif_sdr *sdr)
> >>         for_each_rcar_drif_channel(i, &sdr->cur_ch_mask) {
> >>                 struct rcar_drif *ch = sdr->ch[i];
> >>
> >> -               ch->dmach = dma_request_slave_channel(&ch->pdev->dev, "rx");
> >> -               if (!ch->dmach) {
> >> +               ch->dmach = dma_request_chan(&ch->pdev->dev, "rx");
> >> +               if (IS_ERR(ch->dmach)) {
> >>                         rdrif_err(sdr, "ch%u: dma channel req failed\n", i);
> >
> > Now there is an error code, you might (1) want to print it, and (2) only
> > do so when it is not due to probe deferral:
> >
> >         if (PTR_ERR(ch->dmach) != -EPROBE_DEFER)
> >                 rdrif_err(sdr, "ch%u: dma channel req failed %pe\n",
> > i, ch->dmach);
>
> Yes, this is true.
>
> >
> >> -                       ret = -ENODEV;
> >> +                       ret = PTR_ERR(ch->dmach);
>
> if (ret != -EPROBE_DEFER)
>         rdrif_err(sdr, "ch%u: dma channel req failed (%d)\n", i, ret);
>
> might be simpler.

Sure, checking ret is simpler.
But printing ch->dmach means you can use the new %pe format specifier
to pretty-print the error code.

Gr{oetje,eeting}s,

                        Geert
Peter Ujfalusi Jan. 20, 2020, 12:43 p.m. UTC | #4
On 20/01/2020 14.36, Geert Uytterhoeven wrote:
> Hi Peter,
> 
> On Mon, Jan 20, 2020 at 1:09 PM Peter Ujfalusi <peter.ujfalusi@ti.com> wrote:
>> On 20/01/2020 14.05, Geert Uytterhoeven wrote:
>>> On Tue, Dec 17, 2019 at 11:41 AM Peter Ujfalusi <peter.ujfalusi@ti.com> wrote:
>>>> dma_request_slave_channel() is a wrapper on top of dma_request_chan()
>>>> eating up the error code.
>>>>
>>>> By using dma_request_chan() directly the driver can support deferred
>>>> probing against DMA.
>>>>
>>>> Signed-off-by: Peter Ujfalusi <peter.ujfalusi@ti.com>
>>>
>>> Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>
>>>
>>> One comment below.
>>>
>>>> --- a/drivers/media/platform/rcar_drif.c
>>>> +++ b/drivers/media/platform/rcar_drif.c
>>>> @@ -275,10 +275,10 @@ static int rcar_drif_alloc_dmachannels(struct rcar_drif_sdr *sdr)
>>>>         for_each_rcar_drif_channel(i, &sdr->cur_ch_mask) {
>>>>                 struct rcar_drif *ch = sdr->ch[i];
>>>>
>>>> -               ch->dmach = dma_request_slave_channel(&ch->pdev->dev, "rx");
>>>> -               if (!ch->dmach) {
>>>> +               ch->dmach = dma_request_chan(&ch->pdev->dev, "rx");
>>>> +               if (IS_ERR(ch->dmach)) {
>>>>                         rdrif_err(sdr, "ch%u: dma channel req failed\n", i);
>>>
>>> Now there is an error code, you might (1) want to print it, and (2) only
>>> do so when it is not due to probe deferral:
>>>
>>>         if (PTR_ERR(ch->dmach) != -EPROBE_DEFER)
>>>                 rdrif_err(sdr, "ch%u: dma channel req failed %pe\n",
>>> i, ch->dmach);
>>
>> Yes, this is true.
>>
>>>
>>>> -                       ret = -ENODEV;
>>>> +                       ret = PTR_ERR(ch->dmach);
>>
>> if (ret != -EPROBE_DEFER)
>>         rdrif_err(sdr, "ch%u: dma channel req failed (%d)\n", i, ret);
>>
>> might be simpler.
> 
> Sure, checking ret is simpler.
> But printing ch->dmach means you can use the new %pe format specifier
> to pretty-print the error code.

Ah, I was not aware of this, but there is another issue with the patch:
I need to set the ch->dmach to NULL before jumping to dmach_error..

I'll send v3 in a minute.

> 
> Gr{oetje,eeting}s,
> 
>                         Geert
> 

- Péter

Texas Instruments Finland Oy, Porkkalankatu 22, 00180 Helsinki.
Y-tunnus/Business ID: 0615521-4. Kotipaikka/Domicile: Helsinki

Patch
diff mbox series

diff --git a/drivers/media/platform/rcar_drif.c b/drivers/media/platform/rcar_drif.c
index 0f267a237b42..02ee0e2a09e9 100644
--- a/drivers/media/platform/rcar_drif.c
+++ b/drivers/media/platform/rcar_drif.c
@@ -275,10 +275,10 @@  static int rcar_drif_alloc_dmachannels(struct rcar_drif_sdr *sdr)
 	for_each_rcar_drif_channel(i, &sdr->cur_ch_mask) {
 		struct rcar_drif *ch = sdr->ch[i];
 
-		ch->dmach = dma_request_slave_channel(&ch->pdev->dev, "rx");
-		if (!ch->dmach) {
+		ch->dmach = dma_request_chan(&ch->pdev->dev, "rx");
+		if (IS_ERR(ch->dmach)) {
 			rdrif_err(sdr, "ch%u: dma channel req failed\n", i);
-			ret = -ENODEV;
+			ret = PTR_ERR(ch->dmach);
 			goto dmach_error;
 		}