* [PATCH] PCI: mediatek: Verify whether the free_ck clock is ungated or not
@ 2021-04-29 13:47 Amey Narkhede
2021-04-29 22:38 ` Bjorn Helgaas
0 siblings, 1 reply; 3+ messages in thread
From: Amey Narkhede @ 2021-04-29 13:47 UTC (permalink / raw)
To: Ryder Lee
Cc: Lorenzo Pieralisi, Rob Herring, Bjorn Helgaas, Philipp Zabel,
Matthias Brugger, linux-kernel, linux-pci, linux-mediatek,
linux-arm-kernel, Amey Narkhede
Verify that the free_ck clock is ungated on device resume
by checking return value of clk_prepare_enable().
Signed-off-by: Amey Narkhede <ameynarkhede03@gmail.com>
---
drivers/pci/controller/pcie-mediatek.c | 5 ++++-
1 file changed, 4 insertions(+), 1 deletion(-)
diff --git a/drivers/pci/controller/pcie-mediatek.c b/drivers/pci/controller/pcie-mediatek.c
index 23548b517..9b13214bf 100644
--- a/drivers/pci/controller/pcie-mediatek.c
+++ b/drivers/pci/controller/pcie-mediatek.c
@@ -1154,11 +1154,14 @@ static int __maybe_unused mtk_pcie_resume_noirq(struct device *dev)
{
struct mtk_pcie *pcie = dev_get_drvdata(dev);
struct mtk_pcie_port *port, *tmp;
+ int ret;
if (list_empty(&pcie->ports))
return 0;
- clk_prepare_enable(pcie->free_ck);
+ ret = clk_prepare_enable(pcie->free_ck);
+ if (ret)
+ return ret;
list_for_each_entry_safe(port, tmp, &pcie->ports, list)
mtk_pcie_enable_port(port);
--
2.31.1
^ permalink raw reply related [flat|nested] 3+ messages in thread
* Re: [PATCH] PCI: mediatek: Verify whether the free_ck clock is ungated or not
2021-04-29 13:47 [PATCH] PCI: mediatek: Verify whether the free_ck clock is ungated or not Amey Narkhede
@ 2021-04-29 22:38 ` Bjorn Helgaas
2021-04-30 6:43 ` Amey Narkhede
0 siblings, 1 reply; 3+ messages in thread
From: Bjorn Helgaas @ 2021-04-29 22:38 UTC (permalink / raw)
To: Amey Narkhede
Cc: Ryder Lee, Lorenzo Pieralisi, Rob Herring, Bjorn Helgaas,
Philipp Zabel, Matthias Brugger, linux-kernel, linux-pci,
linux-mediatek, linux-arm-kernel
Can you make the subject say something at a higher level instead of
just paraphrasing the C code? I'm guessing this means resume will now
fail if the clock isn't turned on?
On Thu, Apr 29, 2021 at 07:17:49PM +0530, Amey Narkhede wrote:
> Verify that the free_ck clock is ungated on device resume
> by checking return value of clk_prepare_enable().
Also the commit log -- this doesn't say anything more than the code
itself. Did you find this by tripping over it? Or just by code
inspection? I guess without the check, we continue on and try to
resume, but accesses to PCI devices fail and maybe return ~0 data or
cause machine checks or something?
> Signed-off-by: Amey Narkhede <ameynarkhede03@gmail.com>
> ---
> drivers/pci/controller/pcie-mediatek.c | 5 ++++-
> 1 file changed, 4 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/pci/controller/pcie-mediatek.c b/drivers/pci/controller/pcie-mediatek.c
> index 23548b517..9b13214bf 100644
> --- a/drivers/pci/controller/pcie-mediatek.c
> +++ b/drivers/pci/controller/pcie-mediatek.c
> @@ -1154,11 +1154,14 @@ static int __maybe_unused mtk_pcie_resume_noirq(struct device *dev)
> {
> struct mtk_pcie *pcie = dev_get_drvdata(dev);
> struct mtk_pcie_port *port, *tmp;
> + int ret;
>
> if (list_empty(&pcie->ports))
> return 0;
>
> - clk_prepare_enable(pcie->free_ck);
> + ret = clk_prepare_enable(pcie->free_ck);
> + if (ret)
> + return ret;
Most callers print an error message when clk_prepare_enable() fails.
> list_for_each_entry_safe(port, tmp, &pcie->ports, list)
> mtk_pcie_enable_port(port);
> --
> 2.31.1
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [PATCH] PCI: mediatek: Verify whether the free_ck clock is ungated or not
2021-04-29 22:38 ` Bjorn Helgaas
@ 2021-04-30 6:43 ` Amey Narkhede
0 siblings, 0 replies; 3+ messages in thread
From: Amey Narkhede @ 2021-04-30 6:43 UTC (permalink / raw)
To: Bjorn Helgaas
Cc: Bjorn Helgaas, Ryder Lee, lorenzo.pieralisi, Rob Herring,
Philipp Zabel, Matthias Brugger, linux-kernel, linux-pci,
linux-mediatek, linux-arm-kernel
On 21/04/29 05:38PM, Bjorn Helgaas wrote:
> Can you make the subject say something at a higher level instead of
> just paraphrasing the C code? I'm guessing this means resume will now
> fail if the clock isn't turned on?
>
> On Thu, Apr 29, 2021 at 07:17:49PM +0530, Amey Narkhede wrote:
> > Verify that the free_ck clock is ungated on device resume
> > by checking return value of clk_prepare_enable().
>
> Also the commit log -- this doesn't say anything more than the code
> itself. Did you find this by tripping over it? Or just by code
> inspection? I guess without the check, we continue on and try to
> resume, but accesses to PCI devices fail and maybe return ~0 data or
> cause machine checks or something?
>
I found this with code inspection. Sorry for the unclear commit
messsage. I'll try to clarify it in v2.
> > Signed-off-by: Amey Narkhede <ameynarkhede03@gmail.com>
> > ---
> > drivers/pci/controller/pcie-mediatek.c | 5 ++++-
> > 1 file changed, 4 insertions(+), 1 deletion(-)
> >
> > diff --git a/drivers/pci/controller/pcie-mediatek.c b/drivers/pci/controller/pcie-mediatek.c
> > index 23548b517..9b13214bf 100644
> > --- a/drivers/pci/controller/pcie-mediatek.c
> > +++ b/drivers/pci/controller/pcie-mediatek.c
> > @@ -1154,11 +1154,14 @@ static int __maybe_unused mtk_pcie_resume_noirq(struct device *dev)
> > {
> > struct mtk_pcie *pcie = dev_get_drvdata(dev);
> > struct mtk_pcie_port *port, *tmp;
> > + int ret;
> >
> > if (list_empty(&pcie->ports))
> > return 0;
> >
> > - clk_prepare_enable(pcie->free_ck);
> > + ret = clk_prepare_enable(pcie->free_ck);
> > + if (ret)
> > + return ret;
>
> Most callers print an error message when clk_prepare_enable() fails.
>
[...]
I'll update this in v2.
Thanks,
Amey
^ permalink raw reply [flat|nested] 3+ messages in thread
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2021-04-29 13:47 [PATCH] PCI: mediatek: Verify whether the free_ck clock is ungated or not Amey Narkhede
2021-04-29 22:38 ` Bjorn Helgaas
2021-04-30 6:43 ` Amey Narkhede
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