Hi, On Tue, Apr 23, 2019 at 05:32:15PM +0100, Lorenzo Pieralisi wrote: > On Wed, Mar 13, 2019 at 10:37:52PM +0100, Remi Pommarel wrote: > > When configuring pcie reset pin from gpio (e.g. initially set by > > u-boot) to pcie function this pin goes low for a brief moment > > asserting the PERST# signal. Thus connected device enters fundamental > > reset process and link configuration can only begin after a minimal > > 100ms delay (see [1]). > > > > This makes sure that link is configured after at least 100ms from > > beginning of probe() callback (shortly after the reset pin function > > configuration switch through pinctrl subsytem). > > > > [1] "PCI Express Base Specification", REV. 2.1 > > PCI Express, March 4 2009, 6.6.1 Conventional Reset > > > > Signed-off-by: Remi Pommarel <repk@xxxxxxxxxxxx> > > --- > > drivers/pci/controller/pci-aardvark.c | 17 ++++++++++++++--- > > 1 file changed, 14 insertions(+), 3 deletions(-) > > > > diff --git a/drivers/pci/controller/pci-aardvark.c b/drivers/pci/controller/pci-aardvark.c > > index a30ae7cf8e7e..70a1023d0ef1 100644 > > --- a/drivers/pci/controller/pci-aardvark.c > > +++ b/drivers/pci/controller/pci-aardvark.c > > @@ -177,6 +177,9 @@ > > > > #define PIO_TIMEOUT_MS 1 > > > > +/* Endpoint can take up to 100ms to be ready after a reset */ > > +#define ENDPOINT_RST_MS 100 > > + > > #define LINK_WAIT_MAX_RETRIES 10 > > #define LINK_WAIT_USLEEP_MIN 90000 > > #define LINK_WAIT_USLEEP_MAX 100000 > > @@ -242,8 +245,10 @@ static int advk_pcie_wait_for_link(struct advk_pcie *pcie) > > return -ETIMEDOUT; > > } > > > > -static void advk_pcie_setup_hw(struct advk_pcie *pcie) > > +static void > > +advk_pcie_setup_hw(struct advk_pcie *pcie, unsigned long ep_rdy_time) > > Nit: I prefer the prototype to be in one line, I wrap it for you. > > I am wondering why you need to pass in ep_rdy_time parameter when you > can easily compute it in the function itself. > The only reason for that is because the sooner I get the jiffies the lower the delay has to be. I was trying to reduce the impact of this delay to a minimum, but maybe the improvement is not worth it. -- Remi
