Messages in this thread | | | Subject | Re: [PATCH v3 3/3] PCI: apple: Fix #PERST polarity | From | Luca Ceresoli <> | Date | Tue, 23 Nov 2021 22:36:11 +0100 |
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Hi Mark,
On 23/11/21 19:06, Marc Zyngier wrote: > Now that #PERST is properly defined as active-low in the device tree, > fix the driver to correctly drive the line indemendently of the > implied polarity. > > Fixes: 1e33888fbe44 ("PCI: apple: Add initial hardware bring-up") > Suggested-by: Pali Rohár <pali@kernel.org> > Signed-off-by: Marc Zyngier <maz@kernel.org>
Thanks for quickly addressing this!
Do we need a transition path for backward compatibility with old DTs already around? Something like this [0]. You said [1] the DT actually used is not even the one in the kernel, thus how do we guarantee DT and driver switch to the new polarity all at once?
[0] https://lkml.org/lkml/2021/6/24/1049 [1] https://lkml.org/lkml/2021/11/23/455
> --- > drivers/pci/controller/pcie-apple.c | 4 ++-- > 1 file changed, 2 insertions(+), 2 deletions(-) > > diff --git a/drivers/pci/controller/pcie-apple.c b/drivers/pci/controller/pcie-apple.c > index 957960a733c4..03bc56f39be5 100644 > --- a/drivers/pci/controller/pcie-apple.c > +++ b/drivers/pci/controller/pcie-apple.c > @@ -540,7 +540,7 @@ static int apple_pcie_setup_port(struct apple_pcie *pcie, > rmw_set(PORT_APPCLK_EN, port->base + PORT_APPCLK); > > /* Engage #PERST before setting up the clock */ > > - gpiod_set_value(reset, 0); > + gpiod_set_value(reset, 1); > > ret = apple_pcie_setup_refclk(pcie, port); > if (ret < 0) > @@ -551,7 +551,7 @@ static int apple_pcie_setup_port(struct apple_pcie *pcie, > > /* Deassert #PERST */ > rmw_set(PORT_PERST_OFF, port->base + PORT_PERST); > - gpiod_set_value(reset, 1); > + gpiod_set_value(reset, 0);
Minor note: if it were me I would coalesce patches 1 and 3 together, otherwise we are insisting on a wrong implementation (patch 1) to later fix it all (this patch).
-- Luca
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