RE: [PATCH 12/37] atl1c: restore max-read-request-size in DeviceConrol Register

From: Huang, Xiong
Date: Sat Apr 14 2012 - 06:39:52 EST




> -----Original Message-----
> From: netdev-owner@xxxxxxxxxxxxxxx [mailto:netdev-owner@xxxxxxxxxxxxxxx]
> On Behalf Of Ben Hutchings
> Sent: Saturday, April 14, 2012 1:03
> To: Huang, Xiong
> Cc: davem@xxxxxxxxxxxxx; netdev@xxxxxxxxxxxxxxx; linux-
> kernel@xxxxxxxxxxxxxxx; qca-linux-team; nic-devel; linux-pci
> Subject: Re: [PATCH 12/37] atl1c: restore max-read-request-size in Device
> Conrol Register
>
> On Fri, 2012-04-13 at 08:14 +0800, xiong wrote:
> > in some platforms, we found the max-read-request-size in Device
> > Control Register is set to 0 by (BIOS?) during bootup, this will cause
> > the
> > performance(throughput) very bad.
> > Restore it to a min-value.
> > register definition of REG_DEVICE_CTRL is refined as well.
> [...]
>
> I'm guessing this memory-mapped register is an alias for the PCIe device control
> register. I think you should be using pcie_set_readrq() to ensure that the final
> setting conforms to the device's Max Payload Size and system policy.
>
You are right, I don't know there is a system function to do the right thing. I will revise it.

Thanks
Xiong

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