* [PATCH v1 1/3] PCI: export pci_get_dma_device() helper to other users
@ 2014-07-25 13:31 ` Andy Shevchenko
0 siblings, 0 replies; 9+ messages in thread
From: Andy Shevchenko @ 2014-07-25 13:31 UTC (permalink / raw)
To: Alex Williamson, linux-pci-u79uwXL29TY76Z2rM5mHXA, Bjorn Helgaas,
Mark Brown, Greg Kroah-Hartman, linux-spi-u79uwXL29TY76Z2rM5mHXA,
linux-serial-u79uwXL29TY76Z2rM5mHXA
Cc: Andy Shevchenko
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-VuQAYsv1563Yd54FQh9/CA@public.gmane.org>
---
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);
--
2.0.1
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^ permalink raw reply related [flat|nested] 9+ messages in thread
* [PATCH v1 1/3] PCI: export pci_get_dma_device() helper to other users
@ 2014-07-25 13:31 ` Andy Shevchenko
0 siblings, 0 replies; 9+ messages in thread
From: Andy Shevchenko @ 2014-07-25 13:31 UTC (permalink / raw)
To: Alex Williamson, linux-pci, Bjorn Helgaas, Mark Brown,
Greg Kroah-Hartman, linux-spi, linux-serial
Cc: Andy Shevchenko
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);
--
2.0.1
^ permalink raw reply related [flat|nested] 9+ messages in thread
* [PATCH v1 2/3] pch_uart: use pci_get_dma_device() helper
2014-07-25 13:31 ` Andy Shevchenko
@ 2014-07-25 13:31 ` Andy Shevchenko
-1 siblings, 0 replies; 9+ messages in thread
From: Andy Shevchenko @ 2014-07-25 13:31 UTC (permalink / raw)
To: Alex Williamson, linux-pci-u79uwXL29TY76Z2rM5mHXA, Bjorn Helgaas,
Mark Brown, Greg Kroah-Hartman, linux-spi-u79uwXL29TY76Z2rM5mHXA,
linux-serial-u79uwXL29TY76Z2rM5mHXA
Cc: Andy Shevchenko
Since we have pci_get_dma_device() public we may use it in the drivers. It
considers the function 0 as a DMA controller.
Signed-off-by: Andy Shevchenko <andriy.shevchenko-VuQAYsv1563Yd54FQh9/CA@public.gmane.org>
---
drivers/tty/serial/pch_uart.c | 5 ++---
1 file changed, 2 insertions(+), 3 deletions(-)
diff --git a/drivers/tty/serial/pch_uart.c b/drivers/tty/serial/pch_uart.c
index 2f06e5a..c38fdee 100644
--- a/drivers/tty/serial/pch_uart.c
+++ b/drivers/tty/serial/pch_uart.c
@@ -736,9 +736,8 @@ static void pch_request_dma(struct uart_port *port)
dma_cap_zero(mask);
dma_cap_set(DMA_SLAVE, mask);
- dma_dev = pci_get_bus_and_slot(priv->pdev->bus->number,
- PCI_DEVFN(0xa, 0)); /* Get DMA's dev
- information */
+ dma_dev = pci_get_dma_device(priv->pdev); /* Get DMA's dev information */
+
/* Set Tx DMA */
param = &priv->param_tx;
param->dma_dev = &dma_dev->dev;
--
2.0.1
--
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^ permalink raw reply related [flat|nested] 9+ messages in thread
* [PATCH v1 2/3] pch_uart: use pci_get_dma_device() helper
@ 2014-07-25 13:31 ` Andy Shevchenko
0 siblings, 0 replies; 9+ messages in thread
From: Andy Shevchenko @ 2014-07-25 13:31 UTC (permalink / raw)
To: Alex Williamson, linux-pci, Bjorn Helgaas, Mark Brown,
Greg Kroah-Hartman, linux-spi, linux-serial
Cc: Andy Shevchenko
Since we have pci_get_dma_device() public we may use it in the drivers. It
considers the function 0 as a DMA controller.
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
---
drivers/tty/serial/pch_uart.c | 5 ++---
1 file changed, 2 insertions(+), 3 deletions(-)
diff --git a/drivers/tty/serial/pch_uart.c b/drivers/tty/serial/pch_uart.c
index 2f06e5a..c38fdee 100644
--- a/drivers/tty/serial/pch_uart.c
+++ b/drivers/tty/serial/pch_uart.c
@@ -736,9 +736,8 @@ static void pch_request_dma(struct uart_port *port)
dma_cap_zero(mask);
dma_cap_set(DMA_SLAVE, mask);
- dma_dev = pci_get_bus_and_slot(priv->pdev->bus->number,
- PCI_DEVFN(0xa, 0)); /* Get DMA's dev
- information */
+ dma_dev = pci_get_dma_device(priv->pdev); /* Get DMA's dev information */
+
/* Set Tx DMA */
param = &priv->param_tx;
param->dma_dev = &dma_dev->dev;
--
2.0.1
^ permalink raw reply related [flat|nested] 9+ messages in thread
* [PATCH v1 3/3] spi: topcliff-pch: use pci_get_dma_device() helper
2014-07-25 13:31 ` Andy Shevchenko
(?)
(?)
@ 2014-07-25 13:31 ` Andy Shevchenko
-1 siblings, 0 replies; 9+ messages in thread
From: Andy Shevchenko @ 2014-07-25 13:31 UTC (permalink / raw)
To: Alex Williamson, linux-pci, Bjorn Helgaas, Mark Brown,
Greg Kroah-Hartman, linux-spi, linux-serial
Cc: Andy Shevchenko
Since we have pci_get_dma_device() public we may use it in the drivers. It
considers the function 0 as a DMA controller.
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
---
drivers/spi/spi-topcliff-pch.c | 3 +--
1 file changed, 1 insertion(+), 2 deletions(-)
diff --git a/drivers/spi/spi-topcliff-pch.c b/drivers/spi/spi-topcliff-pch.c
index af51d6a..fe868ce 100644
--- a/drivers/spi/spi-topcliff-pch.c
+++ b/drivers/spi/spi-topcliff-pch.c
@@ -874,8 +874,7 @@ static void pch_spi_request_dma(struct pch_spi_data *data, int bpw)
dma_cap_set(DMA_SLAVE, mask);
/* Get DMA's dev information */
- dma_dev = pci_get_bus_and_slot(data->board_dat->pdev->bus->number,
- PCI_DEVFN(12, 0));
+ dma_dev = pci_get_dma_device(data->board_dat->pdev);
/* Set Tx DMA */
param = &dma->param_tx;
--
2.0.1
^ permalink raw reply related [flat|nested] 9+ messages in thread
* Re: [PATCH v1 1/3] PCI: export pci_get_dma_device() helper to other users
2014-07-25 13:31 ` Andy Shevchenko
` (2 preceding siblings ...)
(?)
@ 2014-07-25 16:58 ` Alex Williamson
[not found] ` <1406307516.1011.21.camel-85EaTFmN5p//9pzu0YdTqQ@public.gmane.org>
-1 siblings, 1 reply; 9+ messages in thread
From: Alex Williamson @ 2014-07-25 16:58 UTC (permalink / raw)
To: Andy Shevchenko
Cc: linux-pci, Bjorn Helgaas, Mark Brown, Greg Kroah-Hartman,
linux-spi, linux-serial
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
^ permalink raw reply [flat|nested] 9+ messages in thread
* Re: [PATCH v1 1/3] PCI: export pci_get_dma_device() helper to other users
2014-07-25 16:58 ` [PATCH v1 1/3] PCI: export pci_get_dma_device() helper to other users Alex Williamson
@ 2014-07-28 9:26 ` Andy Shevchenko
0 siblings, 0 replies; 9+ messages in thread
From: Andy Shevchenko @ 2014-07-28 9:26 UTC (permalink / raw)
To: Alex Williamson
Cc: linux-pci-u79uwXL29TY76Z2rM5mHXA, Bjorn Helgaas, Mark Brown,
Greg Kroah-Hartman, linux-spi-u79uwXL29TY76Z2rM5mHXA,
linux-serial-u79uwXL29TY76Z2rM5mHXA
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-VuQAYsv1563Yd54FQh9/CA@public.gmane.org>
> > ---
> > 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?
--
Andy Shevchenko <andriy.shevchenko-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org>
Intel Finland Oy
--
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^ permalink raw reply [flat|nested] 9+ messages in thread
* Re: [PATCH v1 1/3] PCI: export pci_get_dma_device() helper to other users
@ 2014-07-28 9:26 ` Andy Shevchenko
0 siblings, 0 replies; 9+ messages in thread
From: Andy Shevchenko @ 2014-07-28 9:26 UTC (permalink / raw)
To: Alex Williamson
Cc: linux-pci, Bjorn Helgaas, Mark Brown, Greg Kroah-Hartman,
linux-spi, linux-serial
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?
--
Andy Shevchenko <andriy.shevchenko@intel.com>
Intel Finland Oy
^ permalink raw reply [flat|nested] 9+ messages in thread
* Re: [PATCH v1 1/3] PCI: export pci_get_dma_device() helper to other users
2014-07-28 9:26 ` Andy Shevchenko
(?)
@ 2014-07-28 14:19 ` Alex Williamson
-1 siblings, 0 replies; 9+ messages in thread
From: Alex Williamson @ 2014-07-28 14:19 UTC (permalink / raw)
To: Andy Shevchenko
Cc: linux-pci, Bjorn Helgaas, Mark Brown, Greg Kroah-Hartman,
linux-spi, linux-serial
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
^ permalink raw reply [flat|nested] 9+ messages in thread
end of thread, other threads:[~2014-07-28 14:19 UTC | newest]
Thread overview: 9+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2014-07-25 13:31 [PATCH v1 1/3] PCI: export pci_get_dma_device() helper to other users Andy Shevchenko
2014-07-25 13:31 ` Andy Shevchenko
[not found] ` <1406295104-20082-1-git-send-email-andriy.shevchenko-VuQAYsv1563Yd54FQh9/CA@public.gmane.org>
2014-07-25 13:31 ` [PATCH v1 2/3] pch_uart: use pci_get_dma_device() helper Andy Shevchenko
2014-07-25 13:31 ` Andy Shevchenko
2014-07-25 13:31 ` [PATCH v1 3/3] spi: topcliff-pch: " Andy Shevchenko
2014-07-25 16:58 ` [PATCH v1 1/3] PCI: export pci_get_dma_device() helper to other users Alex Williamson
[not found] ` <1406307516.1011.21.camel-85EaTFmN5p//9pzu0YdTqQ@public.gmane.org>
2014-07-28 9:26 ` Andy Shevchenko
2014-07-28 9:26 ` Andy Shevchenko
2014-07-28 14:19 ` Alex Williamson
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