| Message ID | 1375889649-14638-14-git-send-email-zonque@gmail.com |
|---|---|
| State | New, archived |
| Headers | show |
On Wed, Aug 07, 2013 at 05:34:02PM +0200, Daniel Mack wrote: > This patch contains a cruel hack for looking up the the DMA request > number. The problem here is that the implementation as it stands will > allocate the DMA channel from the user of the ssp port, and hence we > cannot allocate a real channel here. > > Signed-off-by: Daniel Mack <zonque@gmail.com> > --- > Documentation/devicetree/bindings/sound/mrvl,pxa-ssp.txt | 7 +++++++ > sound/soc/pxa/pxa-ssp.c | 12 ++++++++++-- > 2 files changed, 17 insertions(+), 2 deletions(-) So, really this should be part of a generic binding for the SSP device but obviously this is just a virtual device that binds to a generic bit of hardware that can be used for other applications like SPI. For the ASoC case we could instantiate the DAI from the machine driver but that isn't going to work for things like SPI. I'm not 100% sure what the best way to deal with that is. One way of doing this is to have two compatible strings for the same bit of hardware describing the application. I'm not sure that's nice but it works...
On 07.08.2013 18:40, Mark Brown wrote: > On Wed, Aug 07, 2013 at 05:34:02PM +0200, Daniel Mack wrote: >> This patch contains a cruel hack for looking up the the DMA request >> number. The problem here is that the implementation as it stands will >> allocate the DMA channel from the user of the ssp port, and hence we >> cannot allocate a real channel here. >> >> Signed-off-by: Daniel Mack <zonque@gmail.com> >> --- >> Documentation/devicetree/bindings/sound/mrvl,pxa-ssp.txt | 7 +++++++ >> sound/soc/pxa/pxa-ssp.c | 12 ++++++++++-- >> 2 files changed, 17 insertions(+), 2 deletions(-) > > So, really this should be part of a generic binding for the SSP device > but obviously this is just a virtual device that binds to a generic bit > of hardware that can be used for other applications like SPI. For the > ASoC case we could instantiate the DAI from the machine driver but that > isn't going to work for things like SPI. I'm not 100% sure what the > best way to deal with that is. Yes, I pondered over this for a while as well. I thought about having the ssp port instantiated as real device just like we have it now, and then just add a phandle reference in DT from the DAI to the upstream device. Then, we should also allocate the DMA channel from the upstream device and pass it down to the DAI. But then again, the pxa-pcm-lib needs some rework, as it's currently in charge of obtaining and releasing the channel. I wanted to postpone that issue until the rest of the series has settled and limit changes to the bare minimum for now. Does that sound feasible? Daniel
On Thu, Aug 08, 2013 at 11:39:59AM +0200, Daniel Mack wrote: > Then, we should also allocate the DMA channel from the upstream device > and pass it down to the DAI. But then again, the pxa-pcm-lib needs some > rework, as it's currently in charge of obtaining and releasing the channel. > I wanted to postpone that issue until the rest of the series has settled > and limit changes to the bare minimum for now. Does that sound feasible? Yup, the big problem here is the whole DT as ABI thing - what happens in the code isn't so important but the DT is supposed to be stable. Or we could decide that this is one of the cases that's unstable in which case we should probably flag it up in the DT binding document if nothing else.
On 08.08.2013 15:20, Mark Brown wrote: > On Thu, Aug 08, 2013 at 11:39:59AM +0200, Daniel Mack wrote: > >> Then, we should also allocate the DMA channel from the upstream device >> and pass it down to the DAI. But then again, the pxa-pcm-lib needs some >> rework, as it's currently in charge of obtaining and releasing the channel. > >> I wanted to postpone that issue until the rest of the series has settled >> and limit changes to the bare minimum for now. Does that sound feasible? > > Yup, the big problem here is the whole DT as ABI thing - what happens in > the code isn't so important but the DT is supposed to be stable. Or we > could decide that this is one of the cases that's unstable in which case > we should probably flag it up in the DT binding document if nothing else. > Alright, I agreee. It's not much code that was needed to add support for what I proposed, so I added a patch for that to my queue. Thanks for the heads-up. Daniel
diff --git a/Documentation/devicetree/bindings/sound/mrvl,pxa-ssp.txt b/Documentation/devicetree/bindings/sound/mrvl,pxa-ssp.txt new file mode 100644 index 0000000..19d5488 --- /dev/null +++ b/Documentation/devicetree/bindings/sound/mrvl,pxa-ssp.txt @@ -0,0 +1,7 @@ +Marvell PXA SSP CPU DAI bindings + +Required properties: + + compatible Must be "mrvl,pxa-ssp-dai" + + diff --git a/sound/soc/pxa/pxa-ssp.c b/sound/soc/pxa/pxa-ssp.c index 6f4dd75..82b9985 100644 --- a/sound/soc/pxa/pxa-ssp.c +++ b/sound/soc/pxa/pxa-ssp.c @@ -21,6 +21,7 @@ #include <linux/clk.h> #include <linux/io.h> #include <linux/pxa2xx_ssp.h> +#include <linux/of.h> #include <asm/irq.h> @@ -798,6 +799,12 @@ static const struct snd_soc_component_driver pxa_ssp_component = { .name = "pxa-ssp", }; +#ifdef CONFIG_OF +static const struct of_device_id pxa_ssp_of_ids[] = { + { .compatible = "mrvl,pxa-ssp-dai" }, +}; +#endif + static int asoc_ssp_probe(struct platform_device *pdev) { return snd_soc_register_component(&pdev->dev, &pxa_ssp_component, @@ -812,8 +819,9 @@ static int asoc_ssp_remove(struct platform_device *pdev) static struct platform_driver asoc_ssp_driver = { .driver = { - .name = "pxa-ssp-dai", - .owner = THIS_MODULE, + .name = "pxa-ssp-dai", + .owner = THIS_MODULE, + .of_match_table = of_match_ptr(pxa_ssp_of_ids), }, .probe = asoc_ssp_probe,
This patch contains a cruel hack for looking up the the DMA request number. The problem here is that the implementation as it stands will allocate the DMA channel from the user of the ssp port, and hence we cannot allocate a real channel here. Signed-off-by: Daniel Mack <zonque@gmail.com> --- Documentation/devicetree/bindings/sound/mrvl,pxa-ssp.txt | 7 +++++++ sound/soc/pxa/pxa-ssp.c | 12 ++++++++++-- 2 files changed, 17 insertions(+), 2 deletions(-) create mode 100644 Documentation/devicetree/bindings/sound/mrvl,pxa-ssp.txt