Subject: [RFC 5/9] drivers: platform: Configure dma operations at probe time

From: [email-masked] (Sricharan)
Date: Thu, 26 May 2016 09:33:39 +0530

Hi Robin,

>On 25/04/16 16:58, Sricharan R wrote:
>> From: Laurent Pinchart <[email-masked]>
>>
>> Configuring DMA ops at probe time will allow deferring device probe when
>> the IOMMU isn't available yet.
>>
>> Signed-off-by: Laurent Pinchart <[email-masked]>
>> ---
>>   drivers/base/platform.c | 13 +++++++++++++
>>   drivers/of/platform.c   |  7 +++----
>>   2 files changed, 16 insertions(+), 4 deletions(-)
>>
>> diff --git a/drivers/base/platform.c b/drivers/base/platform.c
>> index f437afa..17e64a4 100644
>> --- a/drivers/base/platform.c
>> +++ b/drivers/base/platform.c
>> @@ -557,6 +557,12 @@ static int platform_drv_probe(struct device *_dev)
>>   	if (ret < 0)
>>   		return ret;
>>
>> +	if (of_have_populated_dt()) {
>> +		ret = of_dma_configure_ops(_dev, _dev->of_node);
>> +		if (ret < 0)
>> +			goto done;
>> +	}
>> +
>>   	ret = dev_pm_domain_attach(_dev, true);
>>   	if (ret != -EPROBE_DEFER) {
>>   		if (drv->probe) {
>> @@ -569,6 +575,11 @@ static int platform_drv_probe(struct device *_dev)
>>   		}
>>   	}
>>
>> +	if (of_have_populated_dt()) {
>> +		if (ret)
>> +			of_dma_deconfigure(_dev);
>> +	}
>> +done:
>>   	if (drv->prevent_deferred_probe && ret == -EPROBE_DEFER) {
>>   		dev_warn(_dev, "probe deferral not supported\n");
>>   		ret = -ENXIO;
>> @@ -591,6 +602,8 @@ static int platform_drv_remove(struct device *_dev)
>>   	if (drv->remove)
>>   		ret = drv->remove(dev);
>>   	dev_pm_domain_detach(_dev, true);
>> +	if (of_have_populated_dt())
>> +		of_dma_deconfigure(_dev);
>>
>>   	return ret;
>>   }
>> diff --git a/drivers/of/platform.c b/drivers/of/platform.c
>> index 17ee8d5..12bbc8e1 100644
>> --- a/drivers/of/platform.c
>> +++ b/drivers/of/platform.c
>> @@ -180,11 +180,9 @@ static struct platform_device *of_platform_device_create_pdata(
>>   	dev->dev.bus = &platform_bus_type;
>>   	dev->dev.platform_data = platform_data;
>>   	of_dma_configure_masks(&dev->dev, dev->dev.of_node);
>> -	of_dma_configure_ops(&dev->dev, dev->dev.of_node);
>>   	of_msi_configure(&dev->dev, dev->dev.of_node);
>>
>>   	if (of_device_add(dev) != 0) {
>> -		of_dma_deconfigure(&dev->dev);
>>   		platform_device_put(dev);
>>   		goto err_clear_flag;
>>   	}
>> @@ -481,11 +479,12 @@ static int of_platform_device_destroy(struct device *dev, void *data)
>>   	if (dev->bus == &platform_bus_type)
>>   		platform_device_unregister(to_platform_device(dev));
>>   #ifdef CONFIG_ARM_AMBA
>> -	else if (dev->bus == &amba_bustype)
>> +	else if (dev->bus == &amba_bustype) {
>>   		amba_device_unregister(to_amba_device(dev));
>> +		of_dma_deconfigure(dev);
>> +	}
>
>Note that we definitely need this to happen properly on other buses,
>too. I had something for the AMBA bus back when I last looked at
>this[0], but since then we now have PCI devices going through the
>of_dma_configure() path as well (hence 226d89cbb242).
>
>There's also now some initial ACPI code in flight[1], so it's probably
>about time to take another closer look at how this can be properly
>generalised, but I'm not necessarily averse to starting with a
>DT-focused solution that gets at least half way, then building on top of
>that.

Thanks for direction. I will definitely look at how this can be generalised
 for other buses as well. Based on how that looks, as you said if required
 a DT-only can be done first.

Regards,
 Sricharan