linux-kernel - Re: [PATCH] PCI: tegra194: Remove unnecessary MSI enable reg save and restore

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Message-ID: <32856498-0675-ac5d-81f7-9c2ddb728c50@nvidia.com>
Date:   Mon, 11 Apr 2022 17:03:12 +0530
From:   Vidya Sagar <vidyas@...dia.com>
To:     Lorenzo Pieralisi <lorenzo.pieralisi@....com>,
        Jisheng Zhang <jszhang@...nel.org>
Cc:     Rob Herring <robh@...nel.org>,
        Krzysztof Wilczyński <kw@...ux.com>,
        Bjorn Helgaas <bhelgaas@...gle.com>,
        Thierry Reding <thierry.reding@...il.com>,
        Jonathan Hunter <jonathanh@...dia.com>,
        linux-pci@...r.kernel.org, linux-tegra@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] PCI: tegra194: Remove unnecessary MSI enable reg save and
 restore



On 4/8/2022 5:26 PM, Lorenzo Pieralisi wrote:
> External email: Use caution opening links or attachments
> 
> 
> [+cc Vidya]
> 
> On Sun, Dec 26, 2021 at 03:49:10PM +0800, Jisheng Zhang wrote:
>> The integrated MSI Receiver enable register is always initialized in
>> dw_pcie_setup_rc() which is also called in resume code path, so we
>> don't need to save/restore the enable register during suspend/resume.
>>
>> Signed-off-by: Jisheng Zhang <jszhang@...nel.org>
>> ---
>>   drivers/pci/controller/dwc/pcie-tegra194.c | 9 ---------
>>   1 file changed, 9 deletions(-)
> 
> Need an ACK from Nvidia folks.

Looks good to me.
I couldn't verify it on Nvidia platform as we are facing some issue with 
suspend/resume sequence.
I'll verify and update as soon as I could get suspend/resume working.

Acked-by: Vidya Sagar <vidyas@...dia.com>

- Vidya Sagar
> 
> Lorenzo
> 
>> diff --git a/drivers/pci/controller/dwc/pcie-tegra194.c b/drivers/pci/controller/dwc/pcie-tegra194.c
>> index 904976913081..678898985319 100644
>> --- a/drivers/pci/controller/dwc/pcie-tegra194.c
>> +++ b/drivers/pci/controller/dwc/pcie-tegra194.c
>> @@ -186,8 +186,6 @@
>>   #define N_FTS_VAL                                    52
>>   #define FTS_VAL                                              52
>>
>> -#define PORT_LOGIC_MSI_CTRL_INT_0_EN         0x828
>> -
>>   #define GEN3_EQ_CONTROL_OFF                  0x8a8
>>   #define GEN3_EQ_CONTROL_OFF_PSET_REQ_VEC_SHIFT       8
>>   #define GEN3_EQ_CONTROL_OFF_PSET_REQ_VEC_MASK        GENMASK(23, 8)
>> @@ -2189,9 +2187,6 @@ static int tegra_pcie_dw_suspend_noirq(struct device *dev)
>>        if (!pcie->link_state)
>>                return 0;
>>
>> -     /* Save MSI interrupt vector */
>> -     pcie->msi_ctrl_int = dw_pcie_readl_dbi(&pcie->pci,
>> -                                            PORT_LOGIC_MSI_CTRL_INT_0_EN);
>>        tegra_pcie_downstream_dev_to_D0(pcie);
>>        tegra_pcie_dw_pme_turnoff(pcie);
>>        tegra_pcie_unconfig_controller(pcie);
>> @@ -2223,10 +2218,6 @@ static int tegra_pcie_dw_resume_noirq(struct device *dev)
>>        if (ret < 0)
>>                goto fail_host_init;
>>
>> -     /* Restore MSI interrupt vector */
>> -     dw_pcie_writel_dbi(&pcie->pci, PORT_LOGIC_MSI_CTRL_INT_0_EN,
>> -                        pcie->msi_ctrl_int);
>> -
>>        return 0;
>>
>>   fail_host_init:
>> --
>> 2.34.1
>>