[V2 PATCH 1/5] ACPI / scan: Parse _CCA and setup device coherency

Suravee Suthikulpanit
2015-05-06T04:17:48Z

On 5/5/15 22:13, Hanjun Guo wrote:
> On 2015?05?05? 23:12, Suravee Suthikulpanit wrote:
>> This patch implements support for ACPI _CCA object, which is
>> introduced in
>> ACPIv5.1, can be used for specifying device DMA coherency attribute.
>>
>> The parsing logic traverses device namespace to parse coherency
>> information, and stores it in acpi_device_flags. Then uses it to call
>> arch_setup_dma_ops() when creating each device enumerated in DSDT
>> during ACPI scan.
>>
>> This patch also introduces acpi_dma_is_coherent(), which provides
>> an interface for device drivers to check the coherency information
>> similarly to the of_dma_is_coherent().
>>
>> Signed-off-by: Mark Salter <msalter@redhat.com>
>> Signed-off-by: Suravee Suthikulpanit <Suravee.Suthikulpanit@amd.com>
>> ---
>> NOTE:
>> * Since there seem to be conflict opinions regarding how
>> architecture should handle _CCA=0. So, I am proposing the
>> CONFIG_ARCH_SUPPORT_CCA_ZERO, which can be specified by
>> for each architecture to define behavior of the ACPI
>> scanning code when _CCA=0. Let me know if this is acceptable.
>>
>> drivers/acpi/Kconfig | 6 +++++
>> drivers/acpi/acpi_platform.c | 4 ++-
>> drivers/acpi/scan.c | 62
>> ++++++++++++++++++++++++++++++++++++++++++++
>> include/acpi/acpi_bus.h | 11 +++++++-
>> include/linux/acpi.h | 5 ++++
>> 5 files changed, 86 insertions(+), 2 deletions(-)
>>
>> diff --git a/drivers/acpi/Kconfig b/drivers/acpi/Kconfig
>> index ab2cbb5..dd386e9 100644
>> --- a/drivers/acpi/Kconfig
>> +++ b/drivers/acpi/Kconfig
>> @@ -54,6 +54,12 @@ config ACPI_GENERIC_GSI
>> config ACPI_SYSTEM_POWER_STATES_SUPPORT
>> bool
>>
>> +config ACPI_MUST_HAVE_CCA
>> + bool
>> +
>> +config ACPI_SUPPORT_CCA_ZERO
>> + bool
>> +
>> config ACPI_SLEEP
>> bool
>> depends on SUSPEND || HIBERNATION
>> diff --git a/drivers/acpi/acpi_platform.c b/drivers/acpi/acpi_platform.c
>> index 4bf7559..a6feca4 100644
>> --- a/drivers/acpi/acpi_platform.c
>> +++ b/drivers/acpi/acpi_platform.c
>> @@ -108,9 +108,11 @@ struct platform_device
>> *acpi_create_platform_device(struct acpi_device *adev)
>> if (IS_ERR(pdev))
>> dev_err(&adev->dev, "platform device creation failed: %ld\n",
>> PTR_ERR(pdev));
>> - else
>> + else {
>> + acpi_setup_device_dma(adev, &pdev->dev);
>> dev_dbg(&adev->dev, "created platform device %s\n",
>> dev_name(&pdev->dev));
>> + }
>>
>> kfree(resources);
>> return pdev;
>> diff --git a/drivers/acpi/scan.c b/drivers/acpi/scan.c
>> index 849b699..ac33b29 100644
>> --- a/drivers/acpi/scan.c
>> +++ b/drivers/acpi/scan.c
>> @@ -11,6 +11,7 @@
>> #include <linux/kthread.h>
>> #include <linux/dmi.h>
>> #include <linux/nls.h>
>> +#include <linux/dma-mapping.h>
>>
>> #include <asm/pgtable.h>
>>
>> @@ -2137,6 +2138,66 @@ void acpi_free_pnp_ids(struct acpi_device_pnp
>> *pnp)
>> kfree(pnp->unique_id);
>> }
>>
>> +void acpi_setup_device_dma(struct acpi_device *adev, struct device *dev)
>
> I aasume adev->dev in struct *adev is the same as struct device *dev
> passed here, so
>
>> +{
>> + int coherent = acpi_dma_is_coherent(adev);
>> +
>> + /**
>> + * Currently, we only support DMA for devices that _CCA=1
>> + * since this seems to be the case on most ACPI platforms.
>> + *
>> + * For the case when _CCA=0 (i.e. is_coherent=0 && cca_seen=1),
>> + * we would rely on arch-specific cache maintenance for
>> + * non-coherence DMA operations if architecture enables
>> + * CONFIG_ACPI_SUPPORT_CCA_ZERO.
>> + *
>> + * For the case when _CCA is missing but platform requires it
>> + * (i.e. is_coherent=0 && cca_seen=0), we do not call
>> + * arch_setup_dma_ops() and fallback to arch-specific default
>> + * handling.
>> + */
>> + if (adev->flags.cca_seen) {
>> + if (!coherent && !IS_ENABLED(CONFIG_ACPI_SUPPORT_CCA_ZERO))
>> + return;
>> + arch_setup_dma_ops(dev, 0, 0, NULL, coherent);
>
> how about using &adev->dev here, and just pass struct acpi_device *adev
> for this function?

Actually, I was using arch_setup_device_dma() in multiple places, and
adev->dev is not necessary the same as *dev. However, I am refactoring
this function in V3. Anyways, thanks for reviewing.

Suravee