Re: [PATCH V5] PCI: rcar: Use runtime PM to control controller clock

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Hi Marek,

On Tue, Apr 10, 2018 at 4:31 PM, Marek Vasut <marek.vasut@xxxxxxxxx> wrote:
> On 04/09/2018 02:26 PM, Simon Horman wrote:
>> On Mon, Apr 09, 2018 at 01:47:38PM +0200, Geert Uytterhoeven wrote:
>>> On Mon, Apr 9, 2018 at 1:41 PM, Simon Horman <horms@xxxxxxxxxxxx> wrote:
>>>> On Mon, Apr 09, 2018 at 10:20:05AM +0200, Marek Vasut wrote:
>>>>> On 04/09/2018 10:07 AM, Geert Uytterhoeven wrote:
>>>>>> On Sun, Apr 8, 2018 at 3:09 PM, Marek Vasut <marek.vasut@xxxxxxxxx> wrote:
>>>>>>> From: Dien Pham <dien.pham.ry@xxxxxxxxxxxxxxx>
>>>>>>>
>>>>>>> The controller clock can be switched off during suspend/resume,
>>>>>>> let runtime PM take care of that.
>>>>>>>
>>>>>>> Signed-off-by: Dien Pham <dien.pham.ry@xxxxxxxxxxxxxxx>
>>>>>>> Signed-off-by: Hien Dang <hien.dang.eb@xxxxxxxxxxx>
>>>>>>> Signed-off-by: Marek Vasut <marek.vasut+renesas@xxxxxxxxx>
>>>>>>> Cc: Geert Uytterhoeven <geert+renesas@xxxxxxxxx>
>>>>>>> Cc: Lorenzo Pieralisi <lorenzo.pieralisi@xxxxxxx>
>>>>>>> Cc: Phil Edworthy <phil.edworthy@xxxxxxxxxxx>
>>>>>>> Cc: Simon Horman <horms+renesas@xxxxxxxxxxxx>
>>>>>>> Cc: Wolfram Sang <wsa@xxxxxxxxxxxxx>
>>>>>>> Cc: linux-renesas-soc@xxxxxxxxxxxxxxx
>>>>>>> To: linux-pci@xxxxxxxxxxxxxxx
>>>>>>> ---
>>>>>>> V2: - Reorder the fail path in rcar_pcie_probe() to cater for the
>>>>>>>       reordering of function calls in probe
>>>>>>>     - Dispose of fail_clk in rcar_pcie_get_resources()
>>>>>>> V3: - Fix up the failpath in probe function
>>>>>>> V4: - Rebase on recent linux-next
>>>>>>> V5: - Do not call pci_free_resource_list(&pcie->resources) if
>>>>>>>       rcar_pcie_parse_request_of_pci_ranges() fails, since that
>>>>>>>       functiona calls pci_free_resource_list() already.
>>>>>>
>>>>>> Thanks for the update!
>>>>>>
>>>>>>> --- a/drivers/pci/host/pcie-rcar.c
>>>>>>> +++ b/drivers/pci/host/pcie-rcar.c
>>>>>>
>>>>>>> @@ -1124,22 +1111,22 @@ static int rcar_pcie_probe(struct platform_device *pdev)
>>>>>>>         if (err)
>>>>>>>                 goto err_free_bridge;
>>>>>>>
>>>>>>> +       pm_runtime_enable(pcie->dev);
>>>>>>> +       err = pm_runtime_get_sync(pcie->dev);
>>>>>>> +       if (err < 0) {
>>>>>>> +               dev_err(pcie->dev, "pm_runtime_get_sync failed\n");
>>>>>>> +               goto err_pm_disable;
>>>>>>> +       }
>>>>>>> +
>>>>>>
>>>>>> As you moved the pm_runtime setup up...
>>>>>>
>>>>>>>         err = rcar_pcie_get_resources(pcie);
>>>>>>>         if (err < 0) {
>>>>>>>                 dev_err(dev, "failed to request resources: %d\n", err);
>>>>>>> -               goto err_free_resource_list;
>>>>>>> +               goto err_pm_put;
>>>>>>>         }
>>>>>>>
>>>>>>>         err = rcar_pcie_parse_map_dma_ranges(pcie, dev->of_node);
>>>>>>>         if (err)
>>>>>>> -               goto err_free_resource_list;
>>>>>>> -
>>>>>>> -       pm_runtime_enable(dev);
>>>>>>> -       err = pm_runtime_get_sync(dev);
>>>>>>> -       if (err < 0) {
>>>>>>> -               dev_err(dev, "pm_runtime_get_sync failed\n");
>>>>>>> -               goto err_pm_disable;
>>>>>>> -       }
>>>>>>> +               goto err_pm_put;
>>>>>>>
>>>>>>>         /* Failure to get a link might just be that no cards are inserted */
>>>>>>>         hw_init_fn = of_device_get_match_data(dev);
>>>>>>> @@ -1174,9 +1161,8 @@ static int rcar_pcie_probe(struct platform_device *pdev)
>>>>>>>
>>>>>>>  err_pm_disable:
>>>>>>>         pm_runtime_disable(dev);
>>>>>>
>>>>>> ... shouldn't it be moved down here, for symmetry?
>>>>>
>>>>> I am reasonably certain the failpath should be correct now. Did I still
>>>>> miss something ?
>>>>
>>>> It looks correct to me too. Geert are Marek and I missing something?
>>>
>>> Probably it will still work fine, but after this patch, Runtime PM is enabled
>>> early, and disabled early, which is not symmetrical.
>>>
>>> I like symmetry ;-)
>>
>> Understood. I think that is reasonable.
>> Marek, would you care to respin?
>
> I am looking into the driver, but I fail to see what Geert is trying to
> make me change here.
>
> The pairing looks as follows:
>
> .- rcar_pcie_parse_request_of_pci_ranges()
> |  (pm_runtime_enable is here)
> | .- pm_runtime_get_sync()
> | | .- rcar_pcie_get_resources()

rcar_pcie_get_resources() is called  while the device is runtime-enabled/resumed

> | | |
> | | '- pm_runtime_put()
> | '- pm_runtime_disable() + pci_free_resource_list()

pci_free_resource_list() is called while the device is runtime-disabled.

> '- pci_free_host_bridge()
>
> It looks symmetric to me ...

rcar_pcie_get_resources() is called while the device is
runtime-enabled/resumed,
pci_free_resource_list() is called while the device is runtime-disabled.

Gr{oetje,eeting}s,

                        Geert

-- 
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@xxxxxxxxxxxxxx

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds



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