On Wed, Apr 24, 2019 at 12:29:18AM +0200, Remi Pommarel wrote: > 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).
I am a bit lost, what's the connection between the probe() callback and the reset pin function configuration ? Please elaborate. > > > > > > [1] "PCI Express Base Specification", REV. 2.1 > > > PCI Express, March 4 2009, 6.6.1 Conventional Reset > > > > > > Signed-off-by: Remi Pommarel <r...@triplefau.lt> > > > --- > > > 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. That should just be (roughly) some microseconds unless there is something I am missing. Try to measure it :) More importantly, I would ask you to elaborate a bit more about the logic behind this patch, see above because I need to understand the logic behind pinctrl reset and the probe() hook execution ordering. Thanks, Lorenzo
