linux-kernel - Re: [PATCH 1/1] PCI: qcom: Add early fixup to set the max payload size for IPQ9574

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Message-ID: <20230724140940.GP6291@thinkpad>
Date:   Mon, 24 Jul 2023 19:39:40 +0530
From:   Manivannan Sadhasivam <mani@...nel.org>
To:     Konrad Dybcio <konrad.dybcio@...aro.org>
Cc:     Praveenkumar I <quic_ipkumar@...cinc.com>, agross@...nel.org,
        andersson@...nel.org, lpieralisi@...nel.org, kw@...ux.com,
        robh@...nel.org, bhelgaas@...gle.com, linux-pci@...r.kernel.org,
        linux-arm-msm@...r.kernel.org, linux-kernel@...r.kernel.org,
        quic_varada@...cinc.com, quic_devipriy@...cinc.com
Subject: Re: [PATCH 1/1] PCI: qcom: Add early fixup to set the max payload
 size for IPQ9574

On Mon, Jul 24, 2023 at 06:38:55PM +0530, Manivannan Sadhasivam wrote:
> On Mon, Jul 24, 2023 at 02:53:37PM +0200, Konrad Dybcio wrote:
> > On 24.07.2023 14:47, Praveenkumar I wrote:
> > > Set 256 bytes as payload size for IPQ9574 via early fixup. This allows
> > > PCIe RC to use the max payload size when a capable link partner is
> > > connected.
> > > 
> > > Signed-off-by: Praveenkumar I <quic_ipkumar@...cinc.com>
> > > ---
> > [...]
> > 
> > > 
> > > +static void qcom_fixup_mps_256(struct pci_dev *dev)
> > > +{
> > > +	pcie_set_mps(dev, 256);
> > Looks like setting "dev->pcie_mpss = 1" here would make the PCIe generic
> > code take care of this.
> > 
> 
> Right, also this setting should not be PCI-PCI bridge specific but rather
> controller specific.
> 

Wait, have you tested this patch with PCIe devices having MPS < 256 i.e.,
default 128?

Take a look at this discussion: https://lore.kernel.org/all/20230608093652.1409485-1-vidyas@nvidia.com/

- Mani

> - Mani
> 
> > Konrad
> 
> -- 
> மணிவண்ணன் சதாசிவம்

-- 
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