linux-kernel - Re: [PATCH 01/11] PCI: dwc: Fix port link CSR improper init if CDM check enabled

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Date:   Fri, 17 Feb 2023 13:19:13 +0300
From:   Serge Semin <fancer.lancer@...il.com>
To:     Serge Semin <Sergey.Semin@...kalelectronics.ru>
Cc:     Bjorn Helgaas <bhelgaas@...gle.com>,
        Lorenzo Pieralisi <lorenzo.pieralisi@....com>,
        Cai Huoqing <cai.huoqing@...ux.dev>,
        Jingoo Han <jingoohan1@...il.com>,
        Gustavo Pimentel <gustavo.pimentel@...opsys.com>,
        Vinod Koul <vkoul@...nel.org>,
        Manivannan Sadhasivam <manivannan.sadhasivam@...aro.org>,
        Yoshihiro Shimoda <yoshihiro.shimoda.uh@...esas.com>,
        Rob Herring <robh@...nel.org>,
        Lorenzo Pieralisi <lpieralisi@...nel.org>,
        Krzysztof Wilczyński <kw@...ux.com>,
        Vidya Sagar <vidyas@...dia.com>,
        Manivannan Sadhasivam <mani@...nel.org>,
        Alexey Malahov <Alexey.Malahov@...kalelectronics.ru>,
        Pavel Parkhomenko <Pavel.Parkhomenko@...kalelectronics.ru>,
        linux-pci@...r.kernel.org, dmaengine@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH 01/11] PCI: dwc: Fix port link CSR improper init if CDM
 check enabled

On Fri, Feb 17, 2023 at 12:39:46PM +0300, Serge Semin wrote:
> If CDM_CHECK capability is set then the local variable 'val' will be
> overwritten in the dw_pcie_setup() method in the PL_CHK register
> initialization procedure. Thus further variable usage in the framework of
> the PCIE_PORT_LINK_CONTROL register initialization must imply the variable
> re-initialization. Alas it hasn't been taken into account in the
> commit ec7b952f453c ("PCI: dwc: Always enable CDM check if
> "snps,enable-cdm-check" exists"). Due to that the PCIE_PORT_LINK_CONTROL
> register will be written with improper value in case if the CDM-check is
> enabled. Let's fix this by re-initializing the 'val' variable with the
> PCIE_PORT_LINK_CONTROL CSR content before link-mode initialization.
> 
> Fixes: ec7b952f453c ("PCI: dwc: Always enable CDM check if "snps,enable-cdm-check" exists")
> Signed-off-by: Serge Semin <Sergey.Semin@...kalelectronics.ru>

The same fix was submitted by Yoshihiro a bit earlier:
https://lore.kernel.org/linux-pci/20230216092012.3256440-1-yoshihiro.shimoda.uh@renesas.com/
I've preserved my version of the patch in the series to ease the merge
procedure since the later patch in this patchset may cause conflicts.

-Serge(y)

> ---
>  drivers/pci/controller/dwc/pcie-designware.c | 1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/drivers/pci/controller/dwc/pcie-designware.c b/drivers/pci/controller/dwc/pcie-designware.c
> index 6d5d619ab2e9..3bb9ca14fb9c 100644
> --- a/drivers/pci/controller/dwc/pcie-designware.c
> +++ b/drivers/pci/controller/dwc/pcie-designware.c
> @@ -824,6 +824,7 @@ void dw_pcie_setup(struct dw_pcie *pci)
>  	}
>  
>  	/* Set the number of lanes */
> +	val = dw_pcie_readl_dbi(pci, PCIE_PORT_LINK_CONTROL);
>  	val &= ~PORT_LINK_FAST_LINK_MODE;
>  	val &= ~PORT_LINK_MODE_MASK;
>  	switch (pci->num_lanes) {
> -- 
> 2.39.0
> 
>