linux-kernel - Re: [PATCH] PCI: dw-rockchip: Fix function call sequence in rockchip_pcie_phy

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Message-Id: <D992W9V9ZH2J.2Z2OLK00N0FIU@cknow.org>
Date: Thu, 17 Apr 2025 19:09:46 +0200
From: "Diederik de Haas" <didi.debian@...ow.org>
To: "Dragan Simic" <dsimic@...jaro.org>
Cc: "Lorenzo Pieralisi" <lpieralisi@...nel.org>,
 Krzysztof Wilczyński <kw@...ux.com>, "Bjorn Helgaas"
 <bhelgaas@...gle.com>, "Heiko Stuebner" <heiko@...ech.de>, "Manivannan
 Sadhasivam" <manivannan.sadhasivam@...aro.org>, "Rob Herring"
 <robh@...nel.org>, "Shawn Lin" <shawn.lin@...k-chips.com>, "Niklas Cassel"
 <cassel@...nel.org>, <linux-pci@...r.kernel.org>,
 <linux-arm-kernel@...ts.infradead.org>,
 <linux-rockchip@...ts.infradead.org>, <linux-kernel@...r.kernel.org>,
 <stable@...r.kernel.org>
Subject: Re: [PATCH] PCI: dw-rockchip: Fix function call sequence in
 rockchip_pcie_phy_deinit

Hi Dragan,

On Thu Apr 17, 2025 at 6:20 PM CEST, Dragan Simic wrote:
> On 2025-04-17 16:21, Diederik de Haas wrote:
>> The documentation for the phy_power_off() function explicitly says
>> 
>>   Must be called before phy_exit().
>> 
>> So let's follow that instruction.
>> 
>> Fixes: 0e898eb8df4e ("PCI: rockchip-dwc: Add Rockchip RK356X host
>> controller driver")
>> Cc: stable@...r.kernel.org	# v5.15+
>> Signed-off-by: Diederik de Haas <didi.debian@...ow.org>
>> ---
>>  drivers/pci/controller/dwc/pcie-dw-rockchip.c | 2 +-
>>  1 file changed, 1 insertion(+), 1 deletion(-)
>> 
>> diff --git a/drivers/pci/controller/dwc/pcie-dw-rockchip.c
>> b/drivers/pci/controller/dwc/pcie-dw-rockchip.c
>> index c624b7ebd118..4f92639650e3 100644
>> --- a/drivers/pci/controller/dwc/pcie-dw-rockchip.c
>> +++ b/drivers/pci/controller/dwc/pcie-dw-rockchip.c
>> @@ -410,8 +410,8 @@ static int rockchip_pcie_phy_init(struct
>> rockchip_pcie *rockchip)
>> 
>>  static void rockchip_pcie_phy_deinit(struct rockchip_pcie *rockchip)
>>  {
>> -	phy_exit(rockchip->phy);
>>  	phy_power_off(rockchip->phy);
>> +	phy_exit(rockchip->phy);
>>  }
>> 
>>  static const struct dw_pcie_ops dw_pcie_ops = {
>
> Thanks for the patch, it's looking good to me.  The current state
> of the rockchip_pcie_phy_deinit() function might actually not cause
> issues because the rockchip_pcie_phy_deinit() function is used only
> in the error-handling path in the rockchip_pcie_probe() function,
> so having no runtime errors leads to no possible issues.
>
> However, it doesn't mean it shouldn't be fixed, and it would actually
> be good to dissolve the rockchip_pcie_phy_deinit() function into the
> above-mentioned error-handling path.  It's a short, two-line function
> local to the compile unit, used in a single place only, so dissolving
> it is safe and would actually improve the readability of the code.

This patch came about while looking at [1] "PCI: dw-rockchip: Add system
PM support", which would be the 2nd consumer of the
rockchip_pcie_phy_deinit() function. That patch's commit message has the
following: "tries to reuse possible exist(ing) code"

Being a fan of the DRY principle, that sounds like an excellent idea :-)

So while you're right if there would only be 1 consumer, which is the
case *right now*, given that a 2nd consumer is in the works, I think
it's better to keep it as I've done it now.
Let me know if you disagree (including why).

[1] https://lore.kernel.org/linux-rockchip/1744352048-178994-1-git-send-email-shawn.lin@rock-chips.com/

> Thus, please feel free to include
>
> Reviewed-by: Dragan Simic <dsimic@...jaro.org>

Thanks :-)

Cheers,
  Diederik

> and please consider dissolving the rockchip_pcie_phy_deinit() function
> in the possible v2 of this patch, as suggested above.


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