Re: [PATCH V4] PCI: rcar: Use runtime PM to control controller clock

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On Sun, Apr 01, 2018 at 05:02:07PM +0200, Marek Vasut wrote:
> On 03/19/2018 11:34 AM, Simon Horman wrote:
> > On Mon, Mar 19, 2018 at 10:54:47AM +0100, Marek Vasut wrote:
> >> On 03/19/2018 09:44 AM, Simon Horman wrote:
> >>> On Sun, Mar 18, 2018 at 11:52:09AM +0100, Marek Vasut 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
> >>>> ---
> >>>>  drivers/pci/host/pcie-rcar.c | 40 ++++++++++++----------------------------
> >>>>  1 file changed, 12 insertions(+), 28 deletions(-)
> >>>>
> >>>> diff --git a/drivers/pci/host/pcie-rcar.c b/drivers/pci/host/pcie-rcar.c
> >>>> index b4c4aad2cf66..93d59f15c589 100644
> >>>> --- a/drivers/pci/host/pcie-rcar.c
> >>>> +++ b/drivers/pci/host/pcie-rcar.c
> >>>> @@ -142,7 +142,6 @@ struct rcar_pcie {
> >>>>  	void __iomem		*base;
> >>>>  	struct list_head	resources;
> >>>>  	int			root_bus_nr;
> >>>> -	struct clk		*clk;
> >>>>  	struct clk		*bus_clk;
> >>>>  	struct			rcar_msi msi;
> >>>>  };
> >>>> @@ -914,24 +913,14 @@ static int rcar_pcie_get_resources(struct rcar_pcie *pcie)
> >>>>  	if (IS_ERR(pcie->base))
> >>>>  		return PTR_ERR(pcie->base);
> >>>>  
> >>>> -	pcie->clk = devm_clk_get(dev, "pcie");
> >>>> -	if (IS_ERR(pcie->clk)) {
> >>>> -		dev_err(dev, "cannot get platform clock\n");
> >>>> -		return PTR_ERR(pcie->clk);
> >>>> -	}
> >>>> -	err = clk_prepare_enable(pcie->clk);
> >>>> -	if (err)
> >>>> -		return err;
> >>>> -
> >>>>  	pcie->bus_clk = devm_clk_get(dev, "pcie_bus");
> >>>>  	if (IS_ERR(pcie->bus_clk)) {
> >>>>  		dev_err(dev, "cannot get pcie bus clock\n");
> >>>> -		err = PTR_ERR(pcie->bus_clk);
> >>>> -		goto fail_clk;
> >>>> +		return PTR_ERR(pcie->bus_clk);
> >>>>  	}
> >>>>  	err = clk_prepare_enable(pcie->bus_clk);
> >>>>  	if (err)
> >>>> -		goto fail_clk;
> >>>> +		return err;
> >>>>  
> >>>>  	i = irq_of_parse_and_map(dev->of_node, 0);
> >>>>  	if (!i) {
> >>>> @@ -953,8 +942,6 @@ static int rcar_pcie_get_resources(struct rcar_pcie *pcie)
> >>>>  
> >>>>  err_map_reg:
> >>>>  	clk_disable_unprepare(pcie->bus_clk);
> >>>> -fail_clk:
> >>>> -	clk_disable_unprepare(pcie->clk);
> >>>>  
> >>>>  	return err;
> >>>>  }
> >>>> @@ -1124,22 +1111,22 @@ static int rcar_pcie_probe(struct platform_device *pdev)
> >>>>  	if (err)
> >>>>  		goto err_free_bridge;
> >>>
> >>> This error path now calls pci_free_resource_list() and in this case
> >>> the path is taken if rcar_pcie_parse_request_of_pci_ranges() fails.
> >>> Is that ok?
> >>
> >> I think so, or did I miss something obvious?
> > 
> > I feel that I am the one missing something obvious.
> > But here is what I am worried about:
> > 
> > 1. rcar_pcie_probe() calls rcar_pcie_parse_request_of_pci_ranges()
> > 2. rcar_pcie_parse_request_of_pci_ranges() calls
> >    devm_request_pci_bus_resources() but that fails so
> >    pci_free_resource_list() is called and an error is returned.
> > 3. rcar_pcie_probe() branches to err_free_bridge and calls
> >    pci_free_resource_list() again.
> 
> I see what you mean now, thanks for the details explanation.
> 
> So the change needed here is to move
> pci_free_resource_list(&pcie->resources); above err_free_bridge, so it's
> not called twice, right ?

Yes, I think so.



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