linux-kernel - Re: [PATCH v2 1/2] platform/x86: amd-pmc: Store the pci_dev instance inside struct amd_pmc

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Date:   Fri, 22 Oct 2021 15:46:43 +0530
From:   "Goswami, Sanket" <Sanket.Goswami@....com>
To:     Hans de Goede <hdegoede@...hat.com>, Shyam-sundar.S-k@....com,
        mgross@...ux.intel.com
Cc:     platform-driver-x86@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 1/2] platform/x86: amd-pmc: Store the pci_dev instance
 inside struct amd_pmc_dev

Hi Hans,

On 22-Oct-21 14:21, Hans de Goede wrote:
> [CAUTION: External Email]
> 
> Hi Sanket,
> 
> On 10/22/21 08:55, Goswami, Sanket wrote:
>> Hi Hans,
>>
>> On 21-Oct-21 23:48, Hans de Goede wrote:
>>> [CAUTION: External Email]
>>>
>>> Hi,
>>>
>>> On 10/21/21 11:29, Sanket Goswami wrote:
>>>> Store the root port information in amd_pmc_probe() so that the
>>>> information can be used across multiple routines.
>>>>
>>>> Signed-off-by: Sanket Goswami <Sanket.Goswami@....com>
>>>> ---
>>>> Changes in v2:
>>>> - Store the rdev info in amd_pmc_probe() as suggested by Hans.
>>>
>>> Thank you, but there are still some issues, see below.
>>>
>>>
>>>>  drivers/platform/x86/amd-pmc.c | 4 +++-
>>>>  1 file changed, 3 insertions(+), 1 deletion(-)
>>>>
>>>> diff --git a/drivers/platform/x86/amd-pmc.c b/drivers/platform/x86/amd-pmc.c
>>>> index 55f14bdfdbfd..502f37eaba1f 100644
>>>> --- a/drivers/platform/x86/amd-pmc.c
>>>> +++ b/drivers/platform/x86/amd-pmc.c
>>>> @@ -119,6 +119,7 @@ struct amd_pmc_dev {
>>>>       u16 minor;
>>>>       u16 rev;
>>>>       struct device *dev;
>>>> +     struct pci_dev *rdev;
>>>>       struct mutex lock; /* generic mutex lock */
>>>>  #if IS_ENABLED(CONFIG_DEBUG_FS)
>>>>       struct dentry *dbgfs_dir;
>>>> @@ -482,6 +483,7 @@ static int amd_pmc_probe(struct platform_device *pdev)
>>>>               return -ENODEV;
>>>>       }
>>>>
>>>> +     dev->rdev = rdev;
>>>>       dev->cpu_id = rdev->device;
>>>>       err = pci_write_config_dword(rdev, AMD_PMC_SMU_INDEX_ADDRESS, AMD_PMC_BASE_ADDR_LO);
>>>>       if (err) {
>>>> @@ -512,7 +514,6 @@ static int amd_pmc_probe(struct platform_device *pdev)
>>>>       }
>>>>
>>>>       base_addr_hi = val & AMD_PMC_BASE_ADDR_LO_MASK;
>>>> -     pci_dev_put(dev->rdev);
>>>
>>> The current code here actually reads:
>>>
>>>         pci_dev_put(rdev);
>>>
>>> Note (rdev) not (dev->rdev). I don't know what you based this on, this is weird.
>>
>> rdev is already retrieved before doing this:
>>            pci_dev_put(dev->rdev);
>>
>> i.e.
>> in amd_pmc_probe()
>>
>> rdev = pci_get_domain_bus_and_slot(0, 0, PCI_DEVFN(0, 0));
>>       if (!rdev || !pci_match_id(pmc_pci_ids, rdev)) {
>>               pci_dev_put(rdev);
>>               return -ENODEV;
>>       }
>>
>> after this I am storing rdev in "dev->rdev"
>> i.e.
>> dev->rdev = rdev;
>>
>> after this I am using "dev->rdev" at places where "rdev" was getting used earlier.
>> Do you see any problem?
> 
> What I was trying to say is that the patch does not apply, because it is
> trying to remove the pci_put_dev() line from a block of code like this:
> 
>         base_addr_hi = val & AMD_PMC_BASE_ADDR_LO_MASK;
>         pci_dev_put(dev->rdev);
>         base_addr = ((u64)base_addr_hi << 32 | base_addr_lo);
> 
> But the actual code in platform-drivers-x86/review-hans (and for-next too) has:
> 
>         base_addr_hi = val & AMD_PMC_BASE_ADDR_LO_MASK;
>         pci_dev_put(rdev);
>         base_addr = ((u64)base_addr_hi << 32 | base_addr_lo);
> 
> 
> 
> After your patch using dev->rdev instead of just rdev is fine
> (but please be consistent, which would mean use just rdev everywhere).
> 
> But your patch is removing a line which does not exist in that form,
> IOW it is based on some intermediate version of amd-pmc.c and not
> on the HEAD of platform-drivers-x86/review-hans.

I will rebase it to review-hans branch and will respin a new version.

Thanks,
Sanket