[RESEND]
On 5/5/15 15:36, Rafael J. Wysocki wrote:
On Tuesday, May 05, 2015 10:12:05 AM Suravee Suthikulpanit wrote:
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
ACPI_CCA_REQUIRED maybe?
Sure.
+ bool
+
+config ACPI_SUPPORT_CCA_ZERO
I guess this means "we support devices that can DMA, but are not coherent".
right?
Yes, basically when _CCA=0.
+ 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 {
Please add braces to both branches when making such changes (as per CodingStyle).
OK.
+ acpi_setup_device_dma(adev, &pdev->dev);
Why do we need to do that here (for the second time)?
Because we are calling:
acpi_create_platform_device()
|--> platform_device_register_device_full()
|-->platform_device_alloc()
This creates platform_device, which allocate a new platform_device->dev.
This is not the same as the original acpi_device->dev that was created
during acpi_add_single_object(). So, we have to set up the device
coherency again.
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)
+{
+ 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);
Oh dear.
I made a mistake here. This logic should also call arch_setup_dma_ops()
when cca_seen=0 and coherent=1 (e.g. when _CCA is not required and
default to coherent when it is missing). The current logic doesn't do that.
What about
if (adev->flags.cca_seen && (coherent || IS_ENABLED(CONFIG_ACPI_SUPPORT_CCA_ZERO)))
arch_setup_dma_ops(dev, 0, 0, NULL, coherent);
What about:
if (coherent ||
(adev->flags.cca_seen &&
IS_ENABLED(CONFIG_ACPI_SUPPORT_CCA_ZERO))
arch_setup_dma_ops(dev, 0, 0, NULL, coherent);
I wonder how this is going to affect x86/ia64 too?
This should not affect x86 since arch_setup_dma_ops() is currently not
implement for x86, and default to NOP (see include/linux/dma-mapping.h).
Also, on x86, _CCA is not required and default to 1 if missing.
Thanks,
Suravee
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