From: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
To: Jiaxun Yang <jiaxun.yang@flygoat.com>
Cc: Huacai Chen <chenhuacai@kernel.org>,
linux-pci@vger.kernel.org, bhelgaas@google.com,
linux-kernel@vger.kernel.org, kw@linux.com,
lpieralisi@kernel.org, stable@vger.kernel.org
Subject: Re: [PATCH v2] pci: loongson: Workaround MIPS firmware MRRS settings
Date: Thu, 7 Sep 2023 10:38:05 +0530 [thread overview]
Message-ID: <20230907050805.GA3218@thinkpad> (raw)
In-Reply-To: <6e1bdebf-f335-23a5-c79f-d603c5d0150c@flygoat.com>
On Thu, Sep 07, 2023 at 11:13:00AM +0800, Jiaxun Yang wrote:
>
>
> 在 2023/9/7 9:18, Manivannan Sadhasivam 写道:
> [...]
> > Why do you need to walk through every single device instead of just bridges?
> > I'm not the maintainer, but my suggestion is to go for Huacai Chen's solution.
> Hi Mani,
>
> Thanks for your reply, unfortunately Huacai's solution is impractical in
> this case.
>
> The problem we have, is firmware (or BIOS) setting improper MRRS for devices
> attached under those bridges. So we have to fix up MRRS for every single
> device.
> We can't iterate child device in bridge quirk because there is no guarantee
> that
> bridge will be probed before it's child device, partly due to hotplug.
>
Okay, this clarifies and also warrants improvement in commit message.
You could also use pci_walk_bus() after pci_host_probe() to iterate over the
child devices under root bridge and set MRRS. IMO that would look neat.
- Mani
> This quirk has been in tree for a while, until Huacai refactored it and
> broke some
> systems in 8b3517f88ff2 ("PCI: loongson: Prevent LS7A MRRS increases").
>
> Also to note that ks_pcie_quirk in drivers/pci/controller/dwc/pci-keystone.c
> uses similar approach.
> > This avoids iterating over bridges/devices two times.
> >
> > Also, please rename firmware to BIOS, as firmware commonly represents the
> > software running on PCIe endpoint devices.
> Ack, will fix in next reversion.
>
> Thanks
> - Jiaxun
> >
> > - Mani
> [...]
--
மணிவண்ணன் சதாசிவம்
next prev parent reply other threads:[~2023-09-07 5:08 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-07-25 6:10 [PATCH v2] pci: loongson: Workaround MIPS firmware MRRS settings Jiaxun Yang
2023-08-06 2:20 ` Jiaxun Yang
2023-08-06 14:30 ` Huacai Chen
2023-08-08 7:38 ` Jiaxun Yang
2023-08-29 12:26 ` Linux regression tracking (Thorsten Leemhuis)
2023-08-31 5:31 ` Jiaxun Yang
2023-08-31 6:22 ` Huacai Chen
2023-08-31 8:58 ` Jiaxun Yang
2023-08-31 9:42 ` Huacai Chen
2023-08-31 10:04 ` Jiaxun Yang
2023-09-06 16:11 ` Jiaxun Yang
2023-09-07 1:18 ` Manivannan Sadhasivam
2023-09-07 3:13 ` Jiaxun Yang
2023-09-07 5:08 ` Manivannan Sadhasivam [this message]
2023-09-20 12:33 ` Linux regression tracking (Thorsten Leemhuis)
2023-10-20 11:04 ` Thorsten Leemhuis
2023-10-22 13:36 ` Jiaxun Yang
2023-10-22 13:38 ` Jiaxun Yang
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