Hi Dennis, On 11/02/2015 12:02 PM, Dennis Chen wrote:
On Thu, Oct 29, 2015 at 6:50 AM, Suravee Suthikulpanit <Suravee.Suthikulpanit@xxxxxxx> wrote:From: Jeremy Linton <jeremy.linton@xxxxxxx> ACPI configurations can now mark devices as noncoherent, support that choice. NOTE: This is required to support USB on ARM Juno Development Board. Signed-off-by: Jeremy Linton <jeremy.linton@xxxxxxx> Signed-off-by: Suravee Suthikulpanit <Suravee.Suthikulpanit@xxxxxxx> CC: Bjorn Helgaas <bhelgaas@xxxxxxxxxx> CC: Catalin Marinas <catalin.marinas@xxxxxxx> CC: Rob Herring <robh+dt@xxxxxxxxxx> CC: Will Deacon <will.deacon@xxxxxxx> CC: Rafael J. Wysocki <rjw@xxxxxxxxxxxxx> --- include/acpi/acpi_bus.h | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) diff --git a/include/acpi/acpi_bus.h b/include/acpi/acpi_bus.h index d11eff8..0f131d2 100644 --- a/include/acpi/acpi_bus.h +++ b/include/acpi/acpi_bus.h @@ -407,7 +407,7 @@ static inline bool acpi_check_dma(struct acpi_device *adev, bool *coherent) * case 1. Do not support and disable DMA. * case 2. Support but rely on arch-specific cache maintenance for * non-coherence DMA operations. - * Currently, we implement case 1 above. + * Currently, we implement case 2 above. * * For the case when _CCA is missing (i.e. cca_seen=0) and * platform specifies ACPI_CCA_REQUIRED, we do not support DMA, @@ -415,7 +415,8 @@ static inline bool acpi_check_dma(struct acpi_device *adev, bool *coherent) * * See acpi_init_coherency() for more info. */ - if (adev->flags.coherent_dma) { + if (adev->flags.coherent_dma || + (adev->flags.cca_seen && IS_ENABLED(CONFIG_ARM64))) { ret = true; if (coherent) *coherent = adev->flags.coherent_dma;Hi Suravee, The acpi_check_dma function has been removed in patch 6 of this patch set, why it is still be used here, am I missing something? If the acpi_check_dma will be used in the future, personally I'd like
I think this patch just to let people know that there is case that arch-specific cache maintenance is still needed for ACPI (such as Juno board), and in the later patches will cover this case. acpi_check_dma() will be replaced by acpi_get_dma_attr(), and in acpi_get_dma_attr() will cover that case and will be easily understood. (Suravee, correct me if I'm wrong :) )
to use IS_ENABLED(CONFIG_ACPI_CCA_REQUIRED) while not CONFIG_ARM64 macro here, or since _CCA attribute is arch-specific, it's reasonable to leave the _CCA handling policy to the arch-specific code. For example, with a link weak function like acpi_arch_check_dma() as a default handling if no arch-specific code provided, the actual _CCA handling will be implemented in the ARM, Intel or other Arch if required.
Actually Intel platform don't need _CCA and it's coherent in default, since _CCA is in ACPI spec, I would like it's handled in ACPI core. Thanks Hanjun -- To unsubscribe from this list: send the line "unsubscribe linux-pci" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
