| Message ID | 20150814015004.GA26431@google.com (mailing list archive) |
|---|---|
| State | New, 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; > }
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
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.
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 >
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; }