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SubjectRe: [PATCH v14 05/11] PCI: kirin: give more time for PERST# reset to finish
Em Thu, 21 Oct 2021 13:27:29 +0100
Lorenzo Pieralisi <lorenzo.pieralisi@arm.com> escreveu:

> On Tue, Oct 19, 2021 at 07:06:42AM +0100, Mauro Carvalho Chehab wrote:
> > Before code refactor, the PERST# signals were sent at the
> > end of the power_on logic. Then, the PCI core would probe for
> > the buses and add them.
> >
> > The new logic changed it to send PERST# signals during
> > add_bus operation. That altered the timings.
> >
> > Also, HiKey 970 require a little more waiting time for
> > the PCI bridge - which is outside the SoC - to finish
> > the PERST# reset, and then initialize the eye diagram.
> >
>
> Ok, now you explained it and we should move this explanation
> in the commit log that this change is affecting (I mean we
> should squash this patch with the patch that actually requires it
> - I am not sure whether it is patch 6 or another one).

IMO, having it on a separate patch has the advantage of better documenting
this single line change, but yeah, this is part of the change needed to
handle PERST# on a more portable way to work for both chipsets.

> I can do it for you; I thought it would be a standalone change
> but it actually isn't, because it is brought about by the
> changes you are making and therefore there it belongs.

Feel free to squash this patch if you prefer so. whatever works best for you.

> Thanks for explaining it and apologies for the churn.

No problem.

>
> Lorenzo
>
> > So, increase the waiting time for the PERST# signals to
> > what's required for it to also work with HiKey 970.
> >
> > Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
> > ---
> >
> > See [PATCH v14 00/11] at: https://lore.kernel.org/all/cover.1634622716.git.mchehab+huawei@kernel.org/
> >
> > drivers/pci/controller/dwc/pcie-kirin.c | 2 +-
> > 1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/drivers/pci/controller/dwc/pcie-kirin.c b/drivers/pci/controller/dwc/pcie-kirin.c
> > index de375795a3b8..bc329673632a 100644
> > --- a/drivers/pci/controller/dwc/pcie-kirin.c
> > +++ b/drivers/pci/controller/dwc/pcie-kirin.c
> > @@ -113,7 +113,7 @@ struct kirin_pcie {
> > #define CRGCTRL_PCIE_ASSERT_BIT 0x8c000000
> >
> > /* Time for delay */
> > -#define REF_2_PERST_MIN 20000
> > +#define REF_2_PERST_MIN 21000
> > #define REF_2_PERST_MAX 25000
> > #define PERST_2_ACCESS_MIN 10000
> > #define PERST_2_ACCESS_MAX 12000
> > --
> > 2.31.1
> >

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