| Message ID | 20190522213351.21366-2-repk@triplefau.lt |
|---|---|
| State | Accepted |
| Delegated to: | Lorenzo Pieralisi |
| Headers | show |
| Series | [v2] PCI: aardvark: Wait for endpoint to be ready before training link | expand |
On Wed, May 22, 2019 at 11:33:50PM +0200, 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]). > > Because the pin configuration comes from the "default" pinctrl it is > implicitly configured before the probe callback is called: > > driver_probe_device() > really_probe() > ... > pinctrl_bind_pins() /* Here pin goes from gpio to PCIE reset > function and PERST# is asserted */ > ... > drv->probe() > > [1] "PCI Express Base Specification", REV. 4.0 > PCI Express, February 19 2014, 6.6.1 Conventional Reset > > Signed-off-by: Remi Pommarel <repk@triplefau.lt> > --- > Changes since v1: > - Add a comment about pinctrl implicit pin configuration > - Use more legible msleep > - Use PCI_PM_D3COLD_WAIT macro > > Please note that I will unlikely be able to answer any comments from May > 24th to June 10th. > --- > drivers/pci/controller/pci-aardvark.c | 8 ++++++++ > 1 file changed, 8 insertions(+) > > diff --git a/drivers/pci/controller/pci-aardvark.c b/drivers/pci/controller/pci-aardvark.c > index 134e0306ff00..d998c2b9cd04 100644 > --- a/drivers/pci/controller/pci-aardvark.c > +++ b/drivers/pci/controller/pci-aardvark.c > @@ -324,6 +324,14 @@ static void advk_pcie_setup_hw(struct advk_pcie *pcie) > reg |= PIO_CTRL_ADDR_WIN_DISABLE; > advk_writel(pcie, reg, PIO_CTRL); > > + /* > + * PERST# signal could have been asserted by pinctrl subsystem before > + * probe() callback has been called, making the endpoint going into > + * fundamental reset. As required by PCI Express spec a delay for at > + * least 100ms after such a reset before link training is needed. > + */ > + msleep(PCI_PM_D3COLD_WAIT); > + > /* Start link training */ > reg = advk_readl(pcie, PCIE_CORE_LINK_CTRL_STAT_REG); > reg |= PCIE_CORE_LINK_TRAINING; > -- > 2.20.1 Gentle ping.
On Tue, Aug 06, 2019 at 08:49:46PM +0200, Remi Pommarel wrote: > On Wed, May 22, 2019 at 11:33:50PM +0200, 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]). > > > > Because the pin configuration comes from the "default" pinctrl it is > > implicitly configured before the probe callback is called: > > > > driver_probe_device() > > really_probe() > > ... > > pinctrl_bind_pins() /* Here pin goes from gpio to PCIE reset > > function and PERST# is asserted */ > > ... > > drv->probe() > > > > [1] "PCI Express Base Specification", REV. 4.0 > > PCI Express, February 19 2014, 6.6.1 Conventional Reset > > > > Signed-off-by: Remi Pommarel <repk@triplefau.lt> > > --- > > Changes since v1: > > - Add a comment about pinctrl implicit pin configuration > > - Use more legible msleep > > - Use PCI_PM_D3COLD_WAIT macro > > > > Please note that I will unlikely be able to answer any comments from May > > 24th to June 10th. > > --- > > drivers/pci/controller/pci-aardvark.c | 8 ++++++++ > > 1 file changed, 8 insertions(+) > > > > diff --git a/drivers/pci/controller/pci-aardvark.c b/drivers/pci/controller/pci-aardvark.c > > index 134e0306ff00..d998c2b9cd04 100644 > > --- a/drivers/pci/controller/pci-aardvark.c > > +++ b/drivers/pci/controller/pci-aardvark.c > > @@ -324,6 +324,14 @@ static void advk_pcie_setup_hw(struct advk_pcie *pcie) > > reg |= PIO_CTRL_ADDR_WIN_DISABLE; > > advk_writel(pcie, reg, PIO_CTRL); > > > > + /* > > + * PERST# signal could have been asserted by pinctrl subsystem before > > + * probe() callback has been called, making the endpoint going into > > + * fundamental reset. As required by PCI Express spec a delay for at > > + * least 100ms after such a reset before link training is needed. > > + */ > > + msleep(PCI_PM_D3COLD_WAIT); > > + > > /* Start link training */ > > reg = advk_readl(pcie, PCIE_CORE_LINK_CTRL_STAT_REG); > > reg |= PCIE_CORE_LINK_TRAINING; > > -- > > 2.20.1 > > Gentle ping. Thomas, sorry for the delay, unless you object I would merge this patch, I need your ACK to proceed though. Thanks, Lorenzo
Hello Remi, On Wed, 22 May 2019 23:33:50 +0200 Remi Pommarel <repk@triplefau.lt> 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]). > > Because the pin configuration comes from the "default" pinctrl it is > implicitly configured before the probe callback is called: > > driver_probe_device() > really_probe() > ... > pinctrl_bind_pins() /* Here pin goes from gpio to PCIE reset > function and PERST# is asserted */ > ... > drv->probe() > > [1] "PCI Express Base Specification", REV. 4.0 > PCI Express, February 19 2014, 6.6.1 Conventional Reset > > Signed-off-by: Remi Pommarel <repk@triplefau.lt> It is always a bit annoying to add another 100ms in the boot path, but I don't see an easy alternative solution, so: Acked-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com> Thomas
On Wed, May 22, 2019 at 11:33:50PM +0200, 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]). > > Because the pin configuration comes from the "default" pinctrl it is > implicitly configured before the probe callback is called: > > driver_probe_device() > really_probe() > ... > pinctrl_bind_pins() /* Here pin goes from gpio to PCIE reset > function and PERST# is asserted */ > ... > drv->probe() > > [1] "PCI Express Base Specification", REV. 4.0 > PCI Express, February 19 2014, 6.6.1 Conventional Reset > > Signed-off-by: Remi Pommarel <repk@triplefau.lt> > --- > Changes since v1: > - Add a comment about pinctrl implicit pin configuration > - Use more legible msleep > - Use PCI_PM_D3COLD_WAIT macro > > Please note that I will unlikely be able to answer any comments from May > 24th to June 10th. > --- > drivers/pci/controller/pci-aardvark.c | 8 ++++++++ > 1 file changed, 8 insertions(+) Applied to pci/aardvark, thanks. Lorenzo > diff --git a/drivers/pci/controller/pci-aardvark.c b/drivers/pci/controller/pci-aardvark.c > index 134e0306ff00..d998c2b9cd04 100644 > --- a/drivers/pci/controller/pci-aardvark.c > +++ b/drivers/pci/controller/pci-aardvark.c > @@ -324,6 +324,14 @@ static void advk_pcie_setup_hw(struct advk_pcie *pcie) > reg |= PIO_CTRL_ADDR_WIN_DISABLE; > advk_writel(pcie, reg, PIO_CTRL); > > + /* > + * PERST# signal could have been asserted by pinctrl subsystem before > + * probe() callback has been called, making the endpoint going into > + * fundamental reset. As required by PCI Express spec a delay for at > + * least 100ms after such a reset before link training is needed. > + */ > + msleep(PCI_PM_D3COLD_WAIT); > + > /* Start link training */ > reg = advk_readl(pcie, PCIE_CORE_LINK_CTRL_STAT_REG); > reg |= PCIE_CORE_LINK_TRAINING; > -- > 2.20.1 >
diff --git a/drivers/pci/controller/pci-aardvark.c b/drivers/pci/controller/pci-aardvark.c index 134e0306ff00..d998c2b9cd04 100644 --- a/drivers/pci/controller/pci-aardvark.c +++ b/drivers/pci/controller/pci-aardvark.c @@ -324,6 +324,14 @@ static void advk_pcie_setup_hw(struct advk_pcie *pcie) reg |= PIO_CTRL_ADDR_WIN_DISABLE; advk_writel(pcie, reg, PIO_CTRL); + /* + * PERST# signal could have been asserted by pinctrl subsystem before + * probe() callback has been called, making the endpoint going into + * fundamental reset. As required by PCI Express spec a delay for at + * least 100ms after such a reset before link training is needed. + */ + msleep(PCI_PM_D3COLD_WAIT); + /* Start link training */ reg = advk_readl(pcie, PCIE_CORE_LINK_CTRL_STAT_REG); reg |= PCIE_CORE_LINK_TRAINING;
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]). Because the pin configuration comes from the "default" pinctrl it is implicitly configured before the probe callback is called: driver_probe_device() really_probe() ... pinctrl_bind_pins() /* Here pin goes from gpio to PCIE reset function and PERST# is asserted */ ... drv->probe() [1] "PCI Express Base Specification", REV. 4.0 PCI Express, February 19 2014, 6.6.1 Conventional Reset Signed-off-by: Remi Pommarel <repk@triplefau.lt> --- Changes since v1: - Add a comment about pinctrl implicit pin configuration - Use more legible msleep - Use PCI_PM_D3COLD_WAIT macro Please note that I will unlikely be able to answer any comments from May 24th to June 10th. --- drivers/pci/controller/pci-aardvark.c | 8 ++++++++ 1 file changed, 8 insertions(+)