linux-kernel - Re: [PATCH V7 02/15] PCI: Disable MSI for Tegra194 root port

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Message-ID: <f63051b0-a220-125b-219e-25156d65ea6d@nvidia.com>
Date:   Tue, 21 May 2019 22:17:26 +0530
From:   Vidya Sagar <vidyas@...dia.com>
To:     Thierry Reding <thierry.reding@...il.com>
CC:     <lorenzo.pieralisi@....com>, <bhelgaas@...gle.com>,
        <robh+dt@...nel.org>, <mark.rutland@....com>,
        <jonathanh@...dia.com>, <kishon@...com>, <catalin.marinas@....com>,
        <will.deacon@....com>, <jingoohan1@...il.com>,
        <gustavo.pimentel@...opsys.com>, <mperttunen@...dia.com>,
        <linux-pci@...r.kernel.org>, <devicetree@...r.kernel.org>,
        <linux-tegra@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
        <linux-arm-kernel@...ts.infradead.org>, <kthota@...dia.com>,
        <mmaddireddy@...dia.com>, <sagar.tv@...il.com>
Subject: Re: [PATCH V7 02/15] PCI: Disable MSI for Tegra194 root port

On 5/21/2019 3:57 PM, Thierry Reding wrote:
> On Fri, May 17, 2019 at 06:08:33PM +0530, Vidya Sagar wrote:
>> Tegra194 rootports don't generate MSI interrupts for PME events and hence
>> MSI needs to be disabled for them to avoid root ports service drivers
>> registering their respective ISRs with MSI interrupt.
>>
>> Signed-off-by: Vidya Sagar <vidyas@...dia.com>
>> ---
>> Changes since [v6]:
>> * This is a new patch
>>
>>   drivers/pci/quirks.c | 14 ++++++++++++++
>>   1 file changed, 14 insertions(+)
>>
>> diff --git a/drivers/pci/quirks.c b/drivers/pci/quirks.c
>> index 0f16acc323c6..28f9a0380df5 100644
>> --- a/drivers/pci/quirks.c
>> +++ b/drivers/pci/quirks.c
>> @@ -2592,6 +2592,20 @@ DECLARE_PCI_FIXUP_EARLY(PCI_VENDOR_ID_NVIDIA,
>>   			PCI_DEVICE_ID_NVIDIA_NVENET_15,
>>   			nvenet_msi_disable);
>>   
>> +/*
>> + * Tegra194's PCIe root ports don't generate MSI interrupts for PME events
>> + * instead legacy interrupts are generated. Hence, to avoid service drivers
>> + * registering their respective ISRs for MSIs, need to disable MSI interrupts
>> + * for root ports.
>> + */
>> +static void disable_tegra194_rp_msi(struct pci_dev *dev)
>> +{
>> +	dev->no_msi = 1;
>> +}
>> +DECLARE_PCI_FIXUP_EARLY(PCI_VENDOR_ID_NVIDIA, 0x1ad0, disable_tegra194_rp_msi);
>> +DECLARE_PCI_FIXUP_EARLY(PCI_VENDOR_ID_NVIDIA, 0x1ad1, disable_tegra194_rp_msi);
>> +DECLARE_PCI_FIXUP_EARLY(PCI_VENDOR_ID_NVIDIA, 0x1ad2, disable_tegra194_rp_msi);
>> +
> 
> Later functions in this file seem to use a more consistent naming
> pattern, according to which the name for this would become:
> 
> 	pci_quirk_nvidia_tegra194_disable_rp_msi
> 
> Might be worth considering making this consistent.
> 
> This could also be moved to the DWC driver to restrict this to where it
> is needed. In either case, this seems like a good solution, so:
> 
> Reviewed-by: Thierry Reding <treding@...dia.com>
> 
Ok. I'll move it to DWC driver along with name change for the quirk API.