[PATCH 2/2] arm64: a37xx: pci: Assert PERST# signal when unloading driver

[Pali Rohár]

On Thursday 20 August 2020 09:48:17 Stefan Roese wrote:
> On 20.08.20 09:43, Pali Rohár wrote:
> > On Thursday 20 August 2020 07:05:58 Stefan Roese wrote:
> > > On 19.08.20 15:57, Pali Rohár wrote:
> > > > This change ensures that PCIe card is put into reset state when U-Boot
> > > > stops using it.
> > > > 
> > > > DM_FLAG_OS_PREPARE ensures that U-Boot executes driver's remove callback
> > > > prior booting Linux kernel.
> > > > 
> > > > Linux kernel pci-aardvark driver needs to reset PCIe card via PERST# signal
> > > > prior initializing it. If it does not issue reset then some PCIe cards
> > > > (specially Compex WiFi cards) are not detected at all.
> > > > 
> > > > Putting PCIe card into reset state prior booting Linux kernel would ensure
> > > > that card would be properly reset at time when Linux kernel starts
> > > > initializing pci-aardvark driver.
> > > > 
> > > > Signed-off-by: Pali Rohár <pali at kernel.org>
> > > > ---
> > > >    drivers/pci/pci-aardvark.c | 27 +++++++++++++++++++++------
> > > >    1 file changed, 21 insertions(+), 6 deletions(-)
> > > > 
> > > > diff --git a/drivers/pci/pci-aardvark.c b/drivers/pci/pci-aardvark.c
> > > > index 5b3f23c184..8996be5309 100644
> > > > --- a/drivers/pci/pci-aardvark.c
> > > > +++ b/drivers/pci/pci-aardvark.c
> > > > @@ -148,6 +148,9 @@ struct pcie_advk {
> > > >    	void           *base;
> > > >    	int            first_busno;
> > > >    	struct udevice *dev;
> > > > +#if CONFIG_IS_ENABLED(DM_GPIO)
> > > > +	struct gpio_desc reset_gpio;
> > > > +#endif
> > > >    };
> > > 
> > > Adding more #ifdef's is not recommended. Can't you "depend" this driver
> > > on DM_GPIO in Kconfig instead? Are there any used that don't support
> > > DM_GPIO right now?
> > 
> > I'm not sure if this dependency is what people want. CCing Simon.
> > 
> > In past Simon created commit bcee8d6764f9215f16b393a35581000178633254
> > where described that want to build SPL without GPIO uclass support.
> 
> Is this PCI driver ever built into SPL?

SPL is not used for Espressobin and Turris MOX. But I'm not sure for
other boards. Maybe Simon could provide more information about it.

Basically I added GPIO handling in aardvark driver as it was used on
other place.