| Message ID | 20150814015004.GA26431@google.com (mailing list archive) |
|---|---|
| State | Not Applicable, archived |
| Headers | show |
Here it is again. On Thu, Aug 13, 2015 at 6:50 PM, Bjorn Helgaas <bhelgaas@google.com> wrote: > Hi Suravee, > > On Thu, Aug 13, 2015 at 04:58:45PM +0700, Suravee Suthikulpanit wrote: >> This patch refactors of_pci_dma_configure() into a more generic >> pci_dma_configure(), which can be reused by non-OF code. >> Then, it adds support for setting up PCI device DMA coherency from >> ACPI _CCA object that should normally be specified in the DSDT node >> of its PCI host bridge.. > > Since this does two things: > 1) Rename of_pci_dma_configure() and move it to PCI > 2) Add _CCA support, > maybe it should be split into two patches? > > There are a couple more comments below. > > While looking at this, I thought some of the existing code could be > made simpler and easier to follow. I appended a couple possible patches; > you can incorporate them or ignore them, whatever seems best to you. > > Bjorn > >> Signed-off-by: Suravee Suthikulpanit <Suravee.Suthikulpanit@amd.com> >> CC: Bjorn Helgaas <bhelgaas@google.com> >> CC: Catalin Marinas <catalin.marinas@arm.com> >> CC: Will Deacon <will.deacon@arm.com> >> CC: Rafael J. Wysocki <rjw@rjwysocki.net> >> CC: Rob Herring <robh+dt@kernel.org> >> CC: Murali Karicheri <m-karicheri2@ti.com> >> --- >> Note: According to the ACPI spec, the _CCA attribute is required >> for ARM64. Therefore, this patch is a pre-req for ACPI PCI >> support for ARM64 which is currently in development. >> >> Also, this should not affect other architectures since >> if CCA is not required, the default value is coherent. >> Please see include/acpi/acpi_bus.h: acpi_check_dma() and >> drivers/acpi/scan.c: acpi_init_coherency() for more information >> >> drivers/of/of_pci.c | 20 -------------------- >> drivers/pci/probe.c | 35 +++++++++++++++++++++++++++++++++-- >> include/linux/of_pci.h | 3 --- >> 3 files changed, 33 insertions(+), 25 deletions(-) >> >> diff --git a/drivers/of/of_pci.c b/drivers/of/of_pci.c >> index 5751dc5..b66ee4e 100644 >> --- a/drivers/of/of_pci.c >> +++ b/drivers/of/of_pci.c >> @@ -117,26 +117,6 @@ int of_get_pci_domain_nr(struct device_node *node) >> } >> EXPORT_SYMBOL_GPL(of_get_pci_domain_nr); >> >> -/** >> - * of_pci_dma_configure - Setup DMA configuration >> - * @dev: ptr to pci_dev struct of the PCI device >> - * >> - * Function to update PCI devices's DMA configuration using the same >> - * info from the OF node of host bridge's parent (if any). >> - */ >> -void of_pci_dma_configure(struct pci_dev *pci_dev) >> -{ >> - struct device *dev = &pci_dev->dev; >> - struct device *bridge = pci_get_host_bridge_device(pci_dev); >> - >> - if (!bridge->parent) >> - return; >> - >> - of_dma_configure(dev, bridge->parent->of_node); >> - pci_put_host_bridge_device(bridge); >> -} >> -EXPORT_SYMBOL_GPL(of_pci_dma_configure); >> - >> #if defined(CONFIG_OF_ADDRESS) >> /** >> * of_pci_get_host_bridge_resources - Parse PCI host bridge resources from DT >> diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c >> index cefd636..e2fcd3b 100644 >> --- a/drivers/pci/probe.c >> +++ b/drivers/pci/probe.c >> @@ -6,12 +6,14 @@ >> #include <linux/delay.h> >> #include <linux/init.h> >> #include <linux/pci.h> >> -#include <linux/of_pci.h> >> +#include <linux/of_device.h> >> #include <linux/pci_hotplug.h> >> #include <linux/slab.h> >> #include <linux/module.h> >> #include <linux/cpumask.h> >> #include <linux/pci-aspm.h> >> +#include <linux/acpi.h> >> +#include <linux/property.h> >> #include <asm-generic/pci-bridge.h> >> #include "pci.h" >> >> @@ -1544,6 +1546,35 @@ static void pci_init_capabilities(struct pci_dev *dev) >> pci_enable_acs(dev); >> } >> >> +/** >> + * pci_dma_configure - Setup DMA configuration >> + * @pci_dev: ptr to pci_dev struct of the PCI device >> + * >> + * Function to update PCI devices's DMA configuration using the same >> + * info from the OF node or ACPI node of host bridge's parent (if any). >> + */ >> +static void pci_dma_configure(struct pci_dev *pci_dev) > > Almost all pci_dev pointers in probe.c are named "dev", so I would use > that for this one, too. I probably would just drop the "struct device > *dev" below and use "&dev->dev" the two places you need it. That's a > common idiom in PCI. > >> +{ >> + struct device *dev = &pci_dev->dev; >> + struct device *bridge = pci_get_host_bridge_device(pci_dev); >> + struct acpi_device *adev; >> + bool coherent; >> + >> + if (has_acpi_companion(bridge)) { >> + adev = to_acpi_node(bridge->fwnode); >> + if (acpi_check_dma(adev, &coherent)) >> + arch_setup_dma_ops(dev, 0, 0, NULL, coherent); >> + } else { >> + struct device *host = bridge->parent; >> + if (!host) >> + return; >> + >> + of_dma_configure(dev, host->of_node); >> + } > > Why is this check reversed with respect to device_dma_is_coherent()? > In device_dma_is_coherent(), we first look for an OF property, then look > for ACPI _CCA. But here we check for _CCA, then for OF. > >> + >> + pci_put_host_bridge_device(bridge); >> +} >> + >> void pci_device_add(struct pci_dev *dev, struct pci_bus *bus) >> { >> int ret; >> @@ -1557,7 +1588,7 @@ void pci_device_add(struct pci_dev *dev, struct pci_bus *bus) >> dev->dev.dma_mask = &dev->dma_mask; >> dev->dev.dma_parms = &dev->dma_parms; >> dev->dev.coherent_dma_mask = 0xffffffffull; >> - of_pci_dma_configure(dev); >> + pci_dma_configure(dev); >> >> pci_set_dma_max_seg_size(dev, 65536); >> pci_set_dma_seg_boundary(dev, 0xffffffff); >> diff --git a/include/linux/of_pci.h b/include/linux/of_pci.h >> index 29fd3fe..ce0e5ab 100644 >> --- a/include/linux/of_pci.h >> +++ b/include/linux/of_pci.h >> @@ -16,7 +16,6 @@ int of_pci_get_devfn(struct device_node *np); >> int of_irq_parse_and_map_pci(const struct pci_dev *dev, u8 slot, u8 pin); >> int of_pci_parse_bus_range(struct device_node *node, struct resource *res); >> int of_get_pci_domain_nr(struct device_node *node); >> -void of_pci_dma_configure(struct pci_dev *pci_dev); >> #else >> static inline int of_irq_parse_pci(const struct pci_dev *pdev, struct of_phandle_args *out_irq) >> { >> @@ -51,8 +50,6 @@ of_get_pci_domain_nr(struct device_node *node) >> { >> return -1; >> } >> - >> -static inline void of_pci_dma_configure(struct pci_dev *pci_dev) { } >> #endif >> >> #if defined(CONFIG_OF_ADDRESS) >> -- >> 2.1.0 >> > commit 18183957888f601807ca0e166516ae60f682eb62 > Author: Bjorn Helgaas <bhelgaas@google.com> > Date: Thu Aug 13 20:01:21 2015 -0500 > > ACPI / scan: Move _CCA comments to acpi_init_coherency() > > Move the comments about how we handle _CCA to the code that looks at _CCA, > and fix a couple typos. > > No functional change. > > Signed-off-by: Bjorn Helgaas <bhelgaas@google.com> > > diff --git a/drivers/acpi/scan.c b/drivers/acpi/scan.c > index ec25635..a12e522 100644 > --- a/drivers/acpi/scan.c > +++ b/drivers/acpi/scan.c > @@ -2188,6 +2188,22 @@ static void acpi_init_coherency(struct acpi_device *adev) > acpi_status status; > struct acpi_device *parent = adev->parent; > > + /** > + * Currently, we only support _CCA=1 (i.e. coherent_dma=1) > + * This should be equivalent to specifying dma-coherent for > + * a device in OF. > + * > + * For the case when _CCA=0 (i.e. coherent_dma=0 && cca_seen=1), > + * we have two choices: > + * case 1. Do not support and disable DMA. > + * case 2. Support but rely on arch-specific cache maintenance for > + * non-coherent DMA operations. > + * Currently, we implement case 1 above. > + * > + * For the case when _CCA is missing (i.e. cca_seen=0) and > + * platform specifies ACPI_CCA_REQUIRED, we do not support DMA, > + * and fallback to arch-specific default handling. > + */ > if (parent && parent->flags.cca_seen) { > /* > * From ACPI spec, OSPM will ignore _CCA if an ancestor > diff --git a/include/acpi/acpi_bus.h b/include/acpi/acpi_bus.h > index 83061ca..718942b 100644 > --- a/include/acpi/acpi_bus.h > +++ b/include/acpi/acpi_bus.h > @@ -389,24 +389,6 @@ static inline bool acpi_check_dma(struct acpi_device *adev, bool *coherent) > if (!adev) > return ret; > > - /** > - * Currently, we only support _CCA=1 (i.e. coherent_dma=1) > - * This should be equivalent to specifyig dma-coherent for > - * a device in OF. > - * > - * For the case when _CCA=0 (i.e. coherent_dma=0 && cca_seen=1), > - * There are two cases: > - * 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. > - * > - * For the case when _CCA is missing (i.e. cca_seen=0) and > - * platform specifies ACPI_CCA_REQUIRED, we do not support DMA, > - * and fallback to arch-specific default handling. > - * > - * See acpi_init_coherency() for more info. > - */ > if (adev->flags.coherent_dma) { > ret = true; > if (coherent) > > commit 84cfb2213cd400fef227ec0d7829ec4e12895da9 > Author: Bjorn Helgaas <bhelgaas@google.com> > Date: Thu Aug 13 19:49:52 2015 -0500 > > ACPI / scan: Rename acpi_check_dma() to acpi_dma_is_coherent() > > The name "acpi_check_dma()" doesn't give any much indication about what > exactly it checks. The function also returns information both as a normal > return value and as the "bool *coherent" return parameter. But "*coherent" > doesn't actually give any extra information: it is unchanged when returning > false and set to true when returning true. > > Rename acpi_check_dma() to acpi_dma_is_coherent() so the callers read more > naturally. Drop the return parameter and just use the function return > value. > > Signed-off-by: Bjorn Helgaas <bhelgaas@google.com> > > diff --git a/drivers/acpi/acpi_platform.c b/drivers/acpi/acpi_platform.c > index 06a67d5..fc6138d 100644 > --- a/drivers/acpi/acpi_platform.c > +++ b/drivers/acpi/acpi_platform.c > @@ -103,7 +103,7 @@ struct platform_device *acpi_create_platform_device(struct acpi_device *adev) > pdevinfo.res = resources; > pdevinfo.num_res = count; > pdevinfo.fwnode = acpi_fwnode_handle(adev); > - pdevinfo.dma_mask = acpi_check_dma(adev, NULL) ? DMA_BIT_MASK(32) : 0; > + pdevinfo.dma_mask = acpi_dma_is_coherent(adev) ? DMA_BIT_MASK(32) : 0; > pdev = platform_device_register_full(&pdevinfo); > if (IS_ERR(pdev)) > dev_err(&adev->dev, "platform device creation failed: %ld\n", > diff --git a/drivers/acpi/glue.c b/drivers/acpi/glue.c > index b9657af..89b1cf8 100644 > --- a/drivers/acpi/glue.c > +++ b/drivers/acpi/glue.c > @@ -168,7 +168,6 @@ int acpi_bind_one(struct device *dev, struct acpi_device *acpi_dev) > struct list_head *physnode_list; > unsigned int node_id; > int retval = -EINVAL; > - bool coherent; > > if (has_acpi_companion(dev)) { > if (acpi_dev) { > @@ -225,8 +224,8 @@ int acpi_bind_one(struct device *dev, struct acpi_device *acpi_dev) > if (!has_acpi_companion(dev)) > ACPI_COMPANION_SET(dev, acpi_dev); > > - if (acpi_check_dma(acpi_dev, &coherent)) > - arch_setup_dma_ops(dev, 0, 0, NULL, coherent); > + if (acpi_dma_is_coherent(acpi_dev)) > + arch_setup_dma_ops(dev, 0, 0, NULL, true); > > acpi_physnode_link_name(physical_node_name, node_id); > retval = sysfs_create_link(&acpi_dev->dev.kobj, &dev->kobj, > diff --git a/drivers/base/property.c b/drivers/base/property.c > index f3f6d16..1124130 100644 > --- a/drivers/base/property.c > +++ b/drivers/base/property.c > @@ -523,13 +523,9 @@ EXPORT_SYMBOL_GPL(device_get_child_node_count); > > bool device_dma_is_coherent(struct device *dev) > { > - bool coherent = false; > - > if (IS_ENABLED(CONFIG_OF) && dev->of_node) > - coherent = of_dma_is_coherent(dev->of_node); > - else > - acpi_check_dma(ACPI_COMPANION(dev), &coherent); > + return of_dma_is_coherent(dev->of_node); > > - return coherent; > + return acpi_dma_is_coherent(ACPI_COMPANION(dev)); > } > EXPORT_SYMBOL_GPL(device_dma_is_coherent); > diff --git a/include/acpi/acpi_bus.h b/include/acpi/acpi_bus.h > index 718942b..39f1be6 100644 > --- a/include/acpi/acpi_bus.h > +++ b/include/acpi/acpi_bus.h > @@ -382,19 +382,12 @@ struct acpi_device { > void (*remove)(struct acpi_device *); > }; > > -static inline bool acpi_check_dma(struct acpi_device *adev, bool *coherent) > +static inline bool acpi_dma_is_coherent(struct acpi_device *adev) > { > - bool ret = false; > + if (adev && adev->flags.coherent_dma) > + return true; > > - if (!adev) > - return ret; > - > - if (adev->flags.coherent_dma) { > - ret = true; > - if (coherent) > - *coherent = adev->flags.coherent_dma; > - } > - return ret; > + return false; > } > > static inline bool is_acpi_node(struct fwnode_handle *fwnode) > diff --git a/include/linux/acpi.h b/include/linux/acpi.h > index d2445fa..f29b8b5 100644 > --- a/include/linux/acpi.h > +++ b/include/linux/acpi.h > @@ -562,7 +562,7 @@ static inline int acpi_device_modalias(struct device *dev, > return -ENODEV; > } > > -static inline bool acpi_check_dma(struct acpi_device *adev, bool *coherent) > +static inline bool acpi_dma_is_coherent(struct acpi_device *adev) > { > return false; > } -- To unsubscribe from this list: send the line "unsubscribe linux-acpi" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Hi Bjorn, On 8/25/15 00:32, Bjorn Helgaas wrote: > Here it is again. > > On Thu, Aug 13, 2015 at 6:50 PM, Bjorn Helgaas <bhelgaas@google.com> wrote: >> Hi Suravee, >> >> On Thu, Aug 13, 2015 at 04:58:45PM +0700, Suravee Suthikulpanit wrote: >>> This patch refactors of_pci_dma_configure() into a more generic >>> pci_dma_configure(), which can be reused by non-OF code. >>> Then, it adds support for setting up PCI device DMA coherency from >>> ACPI _CCA object that should normally be specified in the DSDT node >>> of its PCI host bridge.. >> >> Since this does two things: >> 1) Rename of_pci_dma_configure() and move it to PCI >> 2) Add _CCA support, >> maybe it should be split into two patches? Sure, I can take care of that and separate them into two patches. >> There are a couple more comments below. >> >> While looking at this, I thought some of the existing code could be >> made simpler and easier to follow. I appended a couple possible patches; >> you can incorporate them or ignore them, whatever seems best to you. >> >> Bjorn Please see my response below. >> [...] >>> diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c >>> index cefd636..e2fcd3b 100644 >>> --- a/drivers/pci/probe.c >>> +++ b/drivers/pci/probe.c >>> @@ -6,12 +6,14 @@ >>> #include <linux/delay.h> >>> #include <linux/init.h> >>> #include <linux/pci.h> >>> -#include <linux/of_pci.h> >>> +#include <linux/of_device.h> >>> #include <linux/pci_hotplug.h> >>> #include <linux/slab.h> >>> #include <linux/module.h> >>> #include <linux/cpumask.h> >>> #include <linux/pci-aspm.h> >>> +#include <linux/acpi.h> >>> +#include <linux/property.h> >>> #include <asm-generic/pci-bridge.h> >>> #include "pci.h" >>> >>> @@ -1544,6 +1546,35 @@ static void pci_init_capabilities(struct pci_dev *dev) >>> pci_enable_acs(dev); >>> } >>> >>> +/** >>> + * pci_dma_configure - Setup DMA configuration >>> + * @pci_dev: ptr to pci_dev struct of the PCI device >>> + * >>> + * Function to update PCI devices's DMA configuration using the same >>> + * info from the OF node or ACPI node of host bridge's parent (if any). >>> + */ >>> +static void pci_dma_configure(struct pci_dev *pci_dev) >> >> Almost all pci_dev pointers in probe.c are named "dev", so I would use >> that for this one, too. I probably would just drop the "struct device >> *dev" below and use "&dev->dev" the two places you need it. That's a >> common idiom in PCI. >> I'll take care of this. >>> +{ >>> + struct device *dev = &pci_dev->dev; >>> + struct device *bridge = pci_get_host_bridge_device(pci_dev); >>> + struct acpi_device *adev; >>> + bool coherent; >>> + >>> + if (has_acpi_companion(bridge)) { >>> + adev = to_acpi_node(bridge->fwnode); >>> + if (acpi_check_dma(adev, &coherent)) >>> + arch_setup_dma_ops(dev, 0, 0, NULL, coherent); >>> + } else { >>> + struct device *host = bridge->parent; >>> + if (!host) >>> + return; >>> + >>> + of_dma_configure(dev, host->of_node); >>> + } >> >> Why is this check reversed with respect to device_dma_is_coherent()? >> In device_dma_is_coherent(), we first look for an OF property, then look >> for ACPI _CCA. But here we check for _CCA, then for OF. >> I was trying to save some additional logic. But, think again I should not have done so. I'll fix this. >> [...] >> commit 18183957888f601807ca0e166516ae60f682eb62 >> Author: Bjorn Helgaas <bhelgaas@google.com> >> Date: Thu Aug 13 20:01:21 2015 -0500 >> >> ACPI / scan: Move _CCA comments to acpi_init_coherency() >> >> Move the comments about how we handle _CCA to the code that looks at _CCA, >> and fix a couple typos. >> >> No functional change. >> >> Signed-off-by: Bjorn Helgaas <bhelgaas@google.com> >> >> diff --git a/drivers/acpi/scan.c b/drivers/acpi/scan.c >> index ec25635..a12e522 100644 >> --- a/drivers/acpi/scan.c >> +++ b/drivers/acpi/scan.c >> @@ -2188,6 +2188,22 @@ static void acpi_init_coherency(struct acpi_device *adev) >> acpi_status status; >> struct acpi_device *parent = adev->parent; >> >> + /** >> + * Currently, we only support _CCA=1 (i.e. coherent_dma=1) >> + * This should be equivalent to specifying dma-coherent for >> + * a device in OF. >> + * >> + * For the case when _CCA=0 (i.e. coherent_dma=0 && cca_seen=1), >> + * we have two choices: >> + * case 1. Do not support and disable DMA. >> + * case 2. Support but rely on arch-specific cache maintenance for >> + * non-coherent DMA operations. >> + * Currently, we implement case 1 above. >> + * >> + * For the case when _CCA is missing (i.e. cca_seen=0) and >> + * platform specifies ACPI_CCA_REQUIRED, we do not support DMA, >> + * and fallback to arch-specific default handling. >> + */ >> if (parent && parent->flags.cca_seen) { >> /* >> * From ACPI spec, OSPM will ignore _CCA if an ancestor >> diff --git a/include/acpi/acpi_bus.h b/include/acpi/acpi_bus.h >> index 83061ca..718942b 100644 >> --- a/include/acpi/acpi_bus.h >> +++ b/include/acpi/acpi_bus.h >> @@ -389,24 +389,6 @@ static inline bool acpi_check_dma(struct acpi_device *adev, bool *coherent) >> if (!adev) >> return ret; >> >> - /** >> - * Currently, we only support _CCA=1 (i.e. coherent_dma=1) >> - * This should be equivalent to specifyig dma-coherent for >> - * a device in OF. >> - * >> - * For the case when _CCA=0 (i.e. coherent_dma=0 && cca_seen=1), >> - * There are two cases: >> - * 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. >> - * >> - * For the case when _CCA is missing (i.e. cca_seen=0) and >> - * platform specifies ACPI_CCA_REQUIRED, we do not support DMA, >> - * and fallback to arch-specific default handling. >> - * >> - * See acpi_init_coherency() for more info. >> - */ >> if (adev->flags.coherent_dma) { >> ret = true; >> if (coherent) >> Actually, the reason I put the comment in the acpi_check_dma() is because the logic for determining the coherency is in this function, which is separate from the CCA parsing/detection logic. I can probably just get rid of the inline and move the whole function into /driver/acpi/scan.c to make it more readable, and fix the typos. >> commit 84cfb2213cd400fef227ec0d7829ec4e12895da9 >> Author: Bjorn Helgaas <bhelgaas@google.com> >> Date: Thu Aug 13 19:49:52 2015 -0500 >> >> ACPI / scan: Rename acpi_check_dma() to acpi_dma_is_coherent() >> >> The name "acpi_check_dma()" doesn't give any much indication about what >> exactly it checks. The function also returns information both as a normal >> return value and as the "bool *coherent" return parameter. But "*coherent" >> doesn't actually give any extra information: it is unchanged when returning >> false and set to true when returning true. >> >> Rename acpi_check_dma() to acpi_dma_is_coherent() so the callers read more >> naturally. Drop the return parameter and just use the function return >> value. >> >> Signed-off-by: Bjorn Helgaas <bhelgaas@google.com> This was because, at one point, we wanted to be able to differentiate between the case _CCA=0 and missing _CCA in ARM64, where we would support DMA (using arch-specific cache maintenance) if _CCA=0, and disable DMA when missing _CCA on ARM64. It seems like the logic is now required (please see https://www.mail-archive.com/linux-usb@vger.kernel.org/msg62735.html). So, we would need the true/false return, and the coherent variable to be able to differentiate between the two cases. Please let me know what you think. Thanks, Suravee -- To unsubscribe from this list: send the line "unsubscribe linux-acpi" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On Mon, Aug 24, 2015 at 12:09 PM, Suravee Suthikulpanit <Suravee.Suthikulpanit@amd.com> wrote: >>> commit 84cfb2213cd400fef227ec0d7829ec4e12895da9 >>> Author: Bjorn Helgaas <bhelgaas@google.com> >>> Date: Thu Aug 13 19:49:52 2015 -0500 >>> >>> ACPI / scan: Rename acpi_check_dma() to acpi_dma_is_coherent() >>> >>> The name "acpi_check_dma()" doesn't give any much indication about >>> what >>> exactly it checks. The function also returns information both as a >>> normal >>> return value and as the "bool *coherent" return parameter. But >>> "*coherent" >>> doesn't actually give any extra information: it is unchanged when >>> returning >>> false and set to true when returning true. >>> >>> Rename acpi_check_dma() to acpi_dma_is_coherent() so the callers >>> read more >>> naturally. Drop the return parameter and just use the function >>> return >>> value. >>> >>> Signed-off-by: Bjorn Helgaas <bhelgaas@google.com> > > > This was because, at one point, we wanted to be able to differentiate > between the case _CCA=0 and missing _CCA in ARM64, where we would support > DMA (using arch-specific cache maintenance) if _CCA=0, and disable DMA when > missing _CCA on ARM64. > > It seems like the logic is now required (please see > https://www.mail-archive.com/linux-usb@vger.kernel.org/msg62735.html). So, > we would need the true/false return, and the coherent variable to be able to > differentiate between the two cases. > > Please let me know what you think. It's hard for me to comment without seeing the actual patches. I think returning two values (_CCA-seen and coherent) is a confusing interface. -- To unsubscribe from this list: send the line "unsubscribe linux-acpi" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Hi Bjorn, On 8/25/2015 3:14 AM, Bjorn Helgaas wrote: > On Mon, Aug 24, 2015 at 12:09 PM, Suravee Suthikulpanit > <Suravee.Suthikulpanit@amd.com> wrote: > >>>> commit 84cfb2213cd400fef227ec0d7829ec4e12895da9 >>>> Author: Bjorn Helgaas <bhelgaas@google.com> >>>> Date: Thu Aug 13 19:49:52 2015 -0500 >>>> >>>> ACPI / scan: Rename acpi_check_dma() to acpi_dma_is_coherent() >>>> >>>> The name "acpi_check_dma()" doesn't give any much indication about >>>> what >>>> exactly it checks. The function also returns information both as a >>>> normal >>>> return value and as the "bool *coherent" return parameter. But >>>> "*coherent" >>>> doesn't actually give any extra information: it is unchanged when >>>> returning >>>> false and set to true when returning true. >>>> >>>> Rename acpi_check_dma() to acpi_dma_is_coherent() so the callers >>>> read more >>>> naturally. Drop the return parameter and just use the function >>>> return >>>> value. >>>> >>>> Signed-off-by: Bjorn Helgaas <bhelgaas@google.com> >> >> >> This was because, at one point, we wanted to be able to differentiate >> between the case _CCA=0 and missing _CCA in ARM64, where we would support >> DMA (using arch-specific cache maintenance) if _CCA=0, and disable DMA when >> missing _CCA on ARM64. >> >> It seems like the logic is now required (please see >> https://www.mail-archive.com/linux-usb@vger.kernel.org/msg62735.html). So, >> we would need the true/false return, and the coherent variable to be able to >> differentiate between the two cases. >> >> Please let me know what you think. > > It's hard for me to comment without seeing the actual patches. I > think returning two values (_CCA-seen and coherent) is a confusing > interface. Ok. Let me simplify this and send out V2. Thanks, Suravee > -- > To unsubscribe from this list: send the line "unsubscribe linux-pci" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html > -- To unsubscribe from this list: send the line "unsubscribe linux-acpi" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/drivers/acpi/scan.c b/drivers/acpi/scan.c index ec25635..a12e522 100644 --- a/drivers/acpi/scan.c +++ b/drivers/acpi/scan.c @@ -2188,6 +2188,22 @@ static void acpi_init_coherency(struct acpi_device *adev) acpi_status status; struct acpi_device *parent = adev->parent; + /** + * Currently, we only support _CCA=1 (i.e. coherent_dma=1) + * This should be equivalent to specifying dma-coherent for + * a device in OF. + * + * For the case when _CCA=0 (i.e. coherent_dma=0 && cca_seen=1), + * we have two choices: + * case 1. Do not support and disable DMA. + * case 2. Support but rely on arch-specific cache maintenance for + * non-coherent DMA operations. + * Currently, we implement case 1 above. + * + * For the case when _CCA is missing (i.e. cca_seen=0) and + * platform specifies ACPI_CCA_REQUIRED, we do not support DMA, + * and fallback to arch-specific default handling. + */ if (parent && parent->flags.cca_seen) { /* * From ACPI spec, OSPM will ignore _CCA if an ancestor diff --git a/include/acpi/acpi_bus.h b/include/acpi/acpi_bus.h index 83061ca..718942b 100644 --- a/include/acpi/acpi_bus.h +++ b/include/acpi/acpi_bus.h @@ -389,24 +389,6 @@ static inline bool acpi_check_dma(struct acpi_device *adev, bool *coherent) if (!adev) return ret; - /** - * Currently, we only support _CCA=1 (i.e. coherent_dma=1) - * This should be equivalent to specifyig dma-coherent for - * a device in OF. - * - * For the case when _CCA=0 (i.e. coherent_dma=0 && cca_seen=1), - * There are two cases: - * 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. - * - * For the case when _CCA is missing (i.e. cca_seen=0) and - * platform specifies ACPI_CCA_REQUIRED, we do not support DMA, - * and fallback to arch-specific default handling. - * - * See acpi_init_coherency() for more info. - */ if (adev->flags.coherent_dma) { ret = true; if (coherent) commit 84cfb2213cd400fef227ec0d7829ec4e12895da9 Author: Bjorn Helgaas <bhelgaas@google.com> Date: Thu Aug 13 19:49:52 2015 -0500 ACPI / scan: Rename acpi_check_dma() to acpi_dma_is_coherent() The name "acpi_check_dma()" doesn't give any much indication about what exactly it checks. The function also returns information both as a normal return value and as the "bool *coherent" return parameter. But "*coherent" doesn't actually give any extra information: it is unchanged when returning false and set to true when returning true. Rename acpi_check_dma() to acpi_dma_is_coherent() so the callers read more naturally. Drop the return parameter and just use the function return value. Signed-off-by: Bjorn Helgaas <bhelgaas@google.com> diff --git a/drivers/acpi/acpi_platform.c b/drivers/acpi/acpi_platform.c index 06a67d5..fc6138d 100644 --- a/drivers/acpi/acpi_platform.c +++ b/drivers/acpi/acpi_platform.c @@ -103,7 +103,7 @@ struct platform_device *acpi_create_platform_device(struct acpi_device *adev) pdevinfo.res = resources; pdevinfo.num_res = count; pdevinfo.fwnode = acpi_fwnode_handle(adev); - pdevinfo.dma_mask = acpi_check_dma(adev, NULL) ? DMA_BIT_MASK(32) : 0; + pdevinfo.dma_mask = acpi_dma_is_coherent(adev) ? DMA_BIT_MASK(32) : 0; pdev = platform_device_register_full(&pdevinfo); if (IS_ERR(pdev)) dev_err(&adev->dev, "platform device creation failed: %ld\n", diff --git a/drivers/acpi/glue.c b/drivers/acpi/glue.c index b9657af..89b1cf8 100644 --- a/drivers/acpi/glue.c +++ b/drivers/acpi/glue.c @@ -168,7 +168,6 @@ int acpi_bind_one(struct device *dev, struct acpi_device *acpi_dev) struct list_head *physnode_list; unsigned int node_id; int retval = -EINVAL; - bool coherent; if (has_acpi_companion(dev)) { if (acpi_dev) { @@ -225,8 +224,8 @@ int acpi_bind_one(struct device *dev, struct acpi_device *acpi_dev) if (!has_acpi_companion(dev)) ACPI_COMPANION_SET(dev, acpi_dev); - if (acpi_check_dma(acpi_dev, &coherent)) - arch_setup_dma_ops(dev, 0, 0, NULL, coherent); + if (acpi_dma_is_coherent(acpi_dev)) + arch_setup_dma_ops(dev, 0, 0, NULL, true); acpi_physnode_link_name(physical_node_name, node_id); retval = sysfs_create_link(&acpi_dev->dev.kobj, &dev->kobj, diff --git a/drivers/base/property.c b/drivers/base/property.c index f3f6d16..1124130 100644 --- a/drivers/base/property.c +++ b/drivers/base/property.c @@ -523,13 +523,9 @@ EXPORT_SYMBOL_GPL(device_get_child_node_count); bool device_dma_is_coherent(struct device *dev) { - bool coherent = false; - if (IS_ENABLED(CONFIG_OF) && dev->of_node) - coherent = of_dma_is_coherent(dev->of_node); - else - acpi_check_dma(ACPI_COMPANION(dev), &coherent); + return of_dma_is_coherent(dev->of_node); - return coherent; + return acpi_dma_is_coherent(ACPI_COMPANION(dev)); } EXPORT_SYMBOL_GPL(device_dma_is_coherent); diff --git a/include/acpi/acpi_bus.h b/include/acpi/acpi_bus.h index 718942b..39f1be6 100644 --- a/include/acpi/acpi_bus.h +++ b/include/acpi/acpi_bus.h @@ -382,19 +382,12 @@ struct acpi_device { void (*remove)(struct acpi_device *); }; -static inline bool acpi_check_dma(struct acpi_device *adev, bool *coherent) +static inline bool acpi_dma_is_coherent(struct acpi_device *adev) { - bool ret = false; + if (adev && adev->flags.coherent_dma) + return true; - if (!adev) - return ret; - - if (adev->flags.coherent_dma) { - ret = true; - if (coherent) - *coherent = adev->flags.coherent_dma; - } - return ret; + return false; } static inline bool is_acpi_node(struct fwnode_handle *fwnode) diff --git a/include/linux/acpi.h b/include/linux/acpi.h index d2445fa..f29b8b5 100644 --- a/include/linux/acpi.h +++ b/include/linux/acpi.h @@ -562,7 +562,7 @@ static inline int acpi_device_modalias(struct device *dev, return -ENODEV; } -static inline bool acpi_check_dma(struct acpi_device *adev, bool *coherent) +static inline bool acpi_dma_is_coherent(struct acpi_device *adev) { return false; }