| Message ID | 1406295104-20082-1-git-send-email-andriy.shevchenko@linux.intel.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Fri, 2014-07-25 at 16:31 +0300, Andy Shevchenko wrote: > Some chipsets use the function 0 for DMA on other functions of a > multifunctional device. One of the example is Intel EG20T PCH. This is also > applicable to Lynxpoint PCH when LPSS devices are switched to PCI mode. > > This patch exports a useful helper to get a device of the DMA. This device is > needed to request a DMA channel from a proper controller. > > Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com> > --- > drivers/pci/quirks.c | 2 +- > include/linux/pci.h | 9 +++++++++ > 2 files changed, 10 insertions(+), 1 deletion(-) > > diff --git a/drivers/pci/quirks.c b/drivers/pci/quirks.c > index 80c2d01..8352e5b 100644 > --- a/drivers/pci/quirks.c > +++ b/drivers/pci/quirks.c > @@ -3517,7 +3517,7 @@ static struct pci_dev *pci_func_0_dma_source(struct pci_dev *dev) > if (!PCI_FUNC(dev->devfn)) > return pci_dev_get(dev); > > - return pci_get_slot(dev->bus, PCI_DEVFN(PCI_SLOT(dev->devfn), 0)); > + return pci_get_dma_device(dev); > } > > static const struct pci_dev_dma_source { > diff --git a/include/linux/pci.h b/include/linux/pci.h > index 61978a4..86caab7 100644 > --- a/include/linux/pci.h > +++ b/include/linux/pci.h > @@ -1575,6 +1575,15 @@ static inline int pci_dev_specific_acs_enabled(struct pci_dev *dev, > static inline void pci_dev_specific_enable_acs(struct pci_dev *dev) { } > #endif > > +/* > + * Some chipsets use the function 0 for DMA on other functions of a > + * multifunctional device. > + */ > +static inline struct pci_dev *pci_get_dma_device(struct pci_dev *dev) > +{ > + return pci_get_slot(dev->bus, PCI_DEVFN(PCI_SLOT(dev->devfn), 0)); > +} > + > void __iomem *pcim_iomap(struct pci_dev *pdev, int bar, unsigned long maxlen); > void pcim_iounmap(struct pci_dev *pdev, void __iomem *addr); > void __iomem * const *pcim_iomap_table(struct pci_dev *pdev); You've created a very generic function for a very specific problem. I can't just call this on any random device and expect it to work correctly. What about all the other device which use function 1 for their DMA alias. We've just added infrastructure in PCI to support DMA aliases, see pci_for_each_dma_alias(). Please use this instead. Quirks can be added to set the dma_alias_devfn and PCI_DEV_FLAGS_DMA_ALIAS_DEVFN to indicate that it's valid. Thanks, Alex -- To unsubscribe from this list: send the line "unsubscribe linux-spi" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On Fri, 2014-07-25 at 10:58 -0600, Alex Williamson wrote: > On Fri, 2014-07-25 at 16:31 +0300, Andy Shevchenko wrote: > > Some chipsets use the function 0 for DMA on other functions of a > > multifunctional device. One of the example is Intel EG20T PCH. This is also > > applicable to Lynxpoint PCH when LPSS devices are switched to PCI mode. > > > > This patch exports a useful helper to get a device of the DMA. This device is > > needed to request a DMA channel from a proper controller. > > > > Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com> > > --- > > drivers/pci/quirks.c | 2 +- > > include/linux/pci.h | 9 +++++++++ > > 2 files changed, 10 insertions(+), 1 deletion(-) > > > > diff --git a/drivers/pci/quirks.c b/drivers/pci/quirks.c > > index 80c2d01..8352e5b 100644 > > --- a/drivers/pci/quirks.c > > +++ b/drivers/pci/quirks.c > > @@ -3517,7 +3517,7 @@ static struct pci_dev *pci_func_0_dma_source(struct pci_dev *dev) > > if (!PCI_FUNC(dev->devfn)) > > return pci_dev_get(dev); > > > > - return pci_get_slot(dev->bus, PCI_DEVFN(PCI_SLOT(dev->devfn), 0)); > > + return pci_get_dma_device(dev); > > } > > > > static const struct pci_dev_dma_source { > > diff --git a/include/linux/pci.h b/include/linux/pci.h > > index 61978a4..86caab7 100644 > > --- a/include/linux/pci.h > > +++ b/include/linux/pci.h > > @@ -1575,6 +1575,15 @@ static inline int pci_dev_specific_acs_enabled(struct pci_dev *dev, > > static inline void pci_dev_specific_enable_acs(struct pci_dev *dev) { } > > #endif > > > > +/* > > + * Some chipsets use the function 0 for DMA on other functions of a > > + * multifunctional device. > > + */ > > +static inline struct pci_dev *pci_get_dma_device(struct pci_dev *dev) > > +{ > > + return pci_get_slot(dev->bus, PCI_DEVFN(PCI_SLOT(dev->devfn), 0)); > > +} > > + > > void __iomem *pcim_iomap(struct pci_dev *pdev, int bar, unsigned long maxlen); > > void pcim_iounmap(struct pci_dev *pdev, void __iomem *addr); > > void __iomem * const *pcim_iomap_table(struct pci_dev *pdev); > > You've created a very generic function for a very specific problem. I > can't just call this on any random device and expect it to work > correctly. Right. > What about all the other device which use function 1 for > their DMA alias. Hmm... I would like to understand what the difference between DMA alias and the case when we have MFD where function 0 is real DMA controller which serves the other devices in that block is? Another (probably minor) question, why do you still have pci_get_dma_source() function in quirks.c? > We've just added infrastructure in PCI to support DMA > aliases, see pci_for_each_dma_alias(). Please use this instead. Quirks > can be added to set the dma_alias_devfn and > PCI_DEV_FLAGS_DMA_ALIAS_DEVFN to indicate that it's valid. Thanks, Do you mean I have to list all devices that, for example, are listed in the spi-topcliff-pch.c?
On Mon, 2014-07-28 at 12:26 +0300, Andy Shevchenko wrote: > On Fri, 2014-07-25 at 10:58 -0600, Alex Williamson wrote: > > On Fri, 2014-07-25 at 16:31 +0300, Andy Shevchenko wrote: > > > Some chipsets use the function 0 for DMA on other functions of a > > > multifunctional device. One of the example is Intel EG20T PCH. This is also > > > applicable to Lynxpoint PCH when LPSS devices are switched to PCI mode. > > > > > > This patch exports a useful helper to get a device of the DMA. This device is > > > needed to request a DMA channel from a proper controller. > > > > > > Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com> > > > --- > > > drivers/pci/quirks.c | 2 +- > > > include/linux/pci.h | 9 +++++++++ > > > 2 files changed, 10 insertions(+), 1 deletion(-) > > > > > > diff --git a/drivers/pci/quirks.c b/drivers/pci/quirks.c > > > index 80c2d01..8352e5b 100644 > > > --- a/drivers/pci/quirks.c > > > +++ b/drivers/pci/quirks.c > > > @@ -3517,7 +3517,7 @@ static struct pci_dev *pci_func_0_dma_source(struct pci_dev *dev) > > > if (!PCI_FUNC(dev->devfn)) > > > return pci_dev_get(dev); > > > > > > - return pci_get_slot(dev->bus, PCI_DEVFN(PCI_SLOT(dev->devfn), 0)); > > > + return pci_get_dma_device(dev); > > > } > > > > > > static const struct pci_dev_dma_source { > > > diff --git a/include/linux/pci.h b/include/linux/pci.h > > > index 61978a4..86caab7 100644 > > > --- a/include/linux/pci.h > > > +++ b/include/linux/pci.h > > > @@ -1575,6 +1575,15 @@ static inline int pci_dev_specific_acs_enabled(struct pci_dev *dev, > > > static inline void pci_dev_specific_enable_acs(struct pci_dev *dev) { } > > > #endif > > > > > > +/* > > > + * Some chipsets use the function 0 for DMA on other functions of a > > > + * multifunctional device. > > > + */ > > > +static inline struct pci_dev *pci_get_dma_device(struct pci_dev *dev) > > > +{ > > > + return pci_get_slot(dev->bus, PCI_DEVFN(PCI_SLOT(dev->devfn), 0)); > > > +} > > > + > > > void __iomem *pcim_iomap(struct pci_dev *pdev, int bar, unsigned long maxlen); > > > void pcim_iounmap(struct pci_dev *pdev, void __iomem *addr); > > > void __iomem * const *pcim_iomap_table(struct pci_dev *pdev); > > > > You've created a very generic function for a very specific problem. I > > can't just call this on any random device and expect it to work > > correctly. > > Right. > > > What about all the other device which use function 1 for > > their DMA alias. > > Hmm... I would like to understand what the difference between DMA alias > and the case when we have MFD where function 0 is real DMA controller > which serves the other devices in that block is? There is no difference, the PCI DMA alias code is meant to handle any case where the requester ID of a DMA is different from the device that actually initiates the DMA. That may be a different function on a MFD, it may be a non-existent devfn, or it may be an upstream device. Note that using function 0 as the DMA controller for other functions of a MFD is a broken design in a world of IOMMUs. It means that we cannot distinguish transactions from different functions and we need to pre-enable these aliases for the device to work correctly. There's nothing in the PCIe spec that allows an MFD to use the wrong requester ID for DMA. > Another (probably minor) question, why do you still have > pci_get_dma_source() function in quirks.c? It's in the process of being removed https://lkml.org/lkml/2014/5/22/725 > > We've just added infrastructure in PCI to support DMA > > aliases, see pci_for_each_dma_alias(). Please use this instead. Quirks > > can be added to set the dma_alias_devfn and > > PCI_DEV_FLAGS_DMA_ALIAS_DEVFN to indicate that it's valid. Thanks, > > Do you mean I have to list all devices that, for example, are listed in > the spi-topcliff-pch.c? I'm not sure how you'll incorporate it, but creating a pci_get_dma_device() helper which assumes a specific broken relationship for DMA is clearly not a supportable solution. Thanks, Alex -- To unsubscribe from this list: send the line "unsubscribe linux-spi" 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/pci/quirks.c b/drivers/pci/quirks.c index 80c2d01..8352e5b 100644 --- a/drivers/pci/quirks.c +++ b/drivers/pci/quirks.c @@ -3517,7 +3517,7 @@ static struct pci_dev *pci_func_0_dma_source(struct pci_dev *dev) if (!PCI_FUNC(dev->devfn)) return pci_dev_get(dev); - return pci_get_slot(dev->bus, PCI_DEVFN(PCI_SLOT(dev->devfn), 0)); + return pci_get_dma_device(dev); } static const struct pci_dev_dma_source { diff --git a/include/linux/pci.h b/include/linux/pci.h index 61978a4..86caab7 100644 --- a/include/linux/pci.h +++ b/include/linux/pci.h @@ -1575,6 +1575,15 @@ static inline int pci_dev_specific_acs_enabled(struct pci_dev *dev, static inline void pci_dev_specific_enable_acs(struct pci_dev *dev) { } #endif +/* + * Some chipsets use the function 0 for DMA on other functions of a + * multifunctional device. + */ +static inline struct pci_dev *pci_get_dma_device(struct pci_dev *dev) +{ + return pci_get_slot(dev->bus, PCI_DEVFN(PCI_SLOT(dev->devfn), 0)); +} + void __iomem *pcim_iomap(struct pci_dev *pdev, int bar, unsigned long maxlen); void pcim_iounmap(struct pci_dev *pdev, void __iomem *addr); void __iomem * const *pcim_iomap_table(struct pci_dev *pdev);
Some chipsets use the function 0 for DMA on other functions of a multifunctional device. One of the example is Intel EG20T PCH. This is also applicable to Lynxpoint PCH when LPSS devices are switched to PCI mode. This patch exports a useful helper to get a device of the DMA. This device is needed to request a DMA channel from a proper controller. Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com> --- drivers/pci/quirks.c | 2 +- include/linux/pci.h | 9 +++++++++ 2 files changed, 10 insertions(+), 1 deletion(-)