Re: [PATCH -v2 00/16] PCI: Re-factor PCI's 'latency timer' setup

Re: [PATCH -v2 00/16] PCI: Re-factor PCI's 'latency timer' setup

[Jesse Barnes]

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On Fri, 28 Oct 2011 15:47:26 -0600
Myron Stowe <myron.stowe@redhat.com> wrote:

> The 'latency timer' of PCI devices, both Type 0 and Type 1,
> is setup in architecture-specific code [see: pcibios_set_master()].
> There are two approaches being taken by all the architectures - check
> if the 'latency timer' is currently set between 16 and 255 and if not
> bring it within bounds, or, do nothing (and then there is the
> gratuitously different parisc implementation).
> 
> There is nothing architecture-specific about PCI's 'latency timer' so
> this patch pulls the setup functionality up into the PCI core by
> creating a generic 'pcibios_set_master()' function using the '__weak'
> attribute which can be used by all architectures as a default which,
> if necessary, can then be over-ridden by architecture-specific code.

I have acks from Chris, Ralf, and Mike.  Any other arch maintainers
want to ack or nack this before it goes into my -next branch?

Thanks,
-- 
Jesse Barnes, Intel Open Source Technology Center

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Re: [PATCH -v2 00/16] PCI: Re-factor PCI's 'latency timer' setup

[Benjamin Herrenschmidt]

On Fri, 2011-11-11 at 09:59 -0800, Jesse Barnes wrote:
> On Fri, 28 Oct 2011 15:47:26 -0600
> Myron Stowe <myron.stowe@redhat.com> wrote:
> 
> > The 'latency timer' of PCI devices, both Type 0 and Type 1,
> > is setup in architecture-specific code [see: pcibios_set_master()].
> > There are two approaches being taken by all the architectures - check
> > if the 'latency timer' is currently set between 16 and 255 and if not
> > bring it within bounds, or, do nothing (and then there is the
> > gratuitously different parisc implementation).
> > 
> > There is nothing architecture-specific about PCI's 'latency timer' so
> > this patch pulls the setup functionality up into the PCI core by
> > creating a generic 'pcibios_set_master()' function using the '__weak'
> > attribute which can be used by all architectures as a default which,
> > if necessary, can then be over-ridden by architecture-specific code.
> 
> I have acks from Chris, Ralf, and Mike.  Any other arch maintainers
> want to ack or nack this before it goes into my -next branch?

I somewhat missed the original patch. As long as it's a nop for ppc, I
don't care tho :-)

Cheers,
Ben.

Re: [PATCH -v2 01/16] PCI: add declaration for pcibios_set_master() to pci core

[Jesse Barnes]

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On Fri, 28 Oct 2011 15:47:35 -0600
Myron Stowe <myron.stowe@redhat.com> wrote:

> From: Myron Stowe <mstowe@redhat.com>
> 
> Currently, pcibios_set_master() is implemented in architecture-
> specific code.  There is nothing architecture-specific about PCI's
> 'latency timer'.
> 
> This patch adds a declaration for pcibios_set_master() to PCI's core
> in preperation for pulling the function itself up into the core.
> Without the addition of this declaration, subsequent patches that
> remove inline definitions of pcibios_set_master() would be removing
> the only declaration of such.
> 
> No functional change.
> 
> Signed-off-by: Myron Stowe <myron.stowe@redhat.com>
> ---

Ok this series is in -next.  Let's see what breaks this time. :)

Thanks,
-- 
Jesse Barnes, Intel Open Source Technology Center

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Re: [PATCH -v2 01/16] PCI: add declaration for pcibios_set_master() to pci core

[Benjamin Herrenschmidt]

On Mon, 2011-12-05 at 11:06 -0800, Jesse Barnes wrote:
> On Fri, 28 Oct 2011 15:47:35 -0600
> Myron Stowe <myron.stowe@redhat.com> wrote:
> 
> > From: Myron Stowe <mstowe@redhat.com>
> > 
> > Currently, pcibios_set_master() is implemented in architecture-
> > specific code.  There is nothing architecture-specific about PCI's
> > 'latency timer'.
> > 
> > This patch adds a declaration for pcibios_set_master() to PCI's core
> > in preperation for pulling the function itself up into the core.
> > Without the addition of this declaration, subsequent patches that
> > remove inline definitions of pcibios_set_master() would be removing
> > the only declaration of such.
> > 
> > No functional change.
> > 
> > Signed-off-by: Myron Stowe <myron.stowe@redhat.com>
> > ---
> 
> Ok this series is in -next.  Let's see what breaks this time. :)

On the other hand...

One thing that annoys the sh*it out of me is that I cannot use
pcibios_set_master() to establish the DMA/iommu resources for a device,
because set_dma_mask() will be called -after- set_master(), thus I need
to provision every device with 32-bit DMA resources (which can be quite
scarse) just in case the driver doesn't later call set_dma_mask(64-bit).

If only we could reverse the call order... lots of drivers to fix
unfortunately.

In which case I -would- hook into pcibios_set_master()...

Cheers,
Ben.