PCI: brcmstb: Clkreq# accomodations of downstream device

[PATCH v1 3/3] PCI: brcmstb: Allow setting the completion timeout

Posted by Jim Quinlan 2 years, 8 months ago

Since the STB PCIe HW will cause a CPU abort on a completion timeout abort,
we might as well extend the timeout limit.  Further, different devices and
systems may requires a larger or smaller amount for L1SS exit.

Signed-off-by: Jim Quinlan <jim2101024@gmail.com>
---
 drivers/pci/controller/pcie-brcmstb.c | 24 ++++++++++++++++++++++++
 1 file changed, 24 insertions(+)

diff --git a/drivers/pci/controller/pcie-brcmstb.c b/drivers/pci/controller/pcie-brcmstb.c
index 129eee7bdbc1..92d78f4dfaae 100644
--- a/drivers/pci/controller/pcie-brcmstb.c
+++ b/drivers/pci/controller/pcie-brcmstb.c
@@ -1080,6 +1080,29 @@ static void brcm_config_clkreq(struct brcm_pcie *pcie)
 	writel(clkreq_set, pcie->base + PCIE_MISC_HARD_PCIE_HARD_DEBUG);
 }
 
+static void brcm_config_completion_timeout(struct brcm_pcie *pcie)
+{
+	/* TIMEOUT register is two registers before RGR1_SW_INIT_1 */
+	const unsigned int REG_OFFSET = PCIE_RGR1_SW_INIT_1(pcie) - 8;
+	u32 timeout, timeout_msec = 1000;
+	u64 tmp64;
+	int ret;
+
+	ret = of_property_read_u32(pcie->np, "brcm,completion-abort-msecs",
+				   &timeout_msec);
+
+	if (ret && ret != -EINVAL)
+		dev_err(pcie->dev, "bad 'brcm,completion-abort-msecs' prop\n");
+
+	/* Each unit in timeout register is 1/216,000,000 seconds */
+	tmp64 = (u64)216000 * timeout_msec;
+
+	/* Clamp the requested value before writing it */
+	timeout = tmp64 > 0xffffffff ? 0xffffffff : tmp64;
+	timeout = timeout < 0xffff ? 0xffff : timeout;
+	writel(timeout, pcie->base + REG_OFFSET);
+}
+
 static int brcm_pcie_start_link(struct brcm_pcie *pcie)
 {
 	struct device *dev = pcie->dev;
@@ -1110,6 +1133,7 @@ static int brcm_pcie_start_link(struct brcm_pcie *pcie)
 		return -ENODEV;
 	}
 
+	brcm_config_completion_timeout(pcie);
 	brcm_config_clkreq(pcie);
 
 	if (pcie->gen)
-- 
2.17.1

Re: [PATCH v1 3/3] PCI: brcmstb: Allow setting the completion timeout

Posted by Stefan Wahren 2 years, 8 months ago

Hi Jim,

Am 06.04.23 um 14:46 schrieb Jim Quinlan:
> Since the STB PCIe HW will cause a CPU abort on a completion timeout abort,
> we might as well extend the timeout limit.  Further, different devices and
> systems may requires a larger or smaller amount for L1SS exit.
> 
> Signed-off-by: Jim Quinlan <jim2101024@gmail.com>
> ---
>   drivers/pci/controller/pcie-brcmstb.c | 24 ++++++++++++++++++++++++
>   1 file changed, 24 insertions(+)
> 
> diff --git a/drivers/pci/controller/pcie-brcmstb.c b/drivers/pci/controller/pcie-brcmstb.c
> index 129eee7bdbc1..92d78f4dfaae 100644
> --- a/drivers/pci/controller/pcie-brcmstb.c
> +++ b/drivers/pci/controller/pcie-brcmstb.c
> @@ -1080,6 +1080,29 @@ static void brcm_config_clkreq(struct brcm_pcie *pcie)
>   	writel(clkreq_set, pcie->base + PCIE_MISC_HARD_PCIE_HARD_DEBUG);
>   }
>   
> +static void brcm_config_completion_timeout(struct brcm_pcie *pcie)
> +{
> +	/* TIMEOUT register is two registers before RGR1_SW_INIT_1 */
> +	const unsigned int REG_OFFSET = PCIE_RGR1_SW_INIT_1(pcie) - 8;
> +	u32 timeout, timeout_msec = 1000;
> +	u64 tmp64;
> +	int ret;
> +
> +	ret = of_property_read_u32(pcie->np, "brcm,completion-abort-msecs",
> +				   &timeout_msec);
> +
> +	if (ret && ret != -EINVAL)
> +		dev_err(pcie->dev, "bad 'brcm,completion-abort-msecs' prop\n");

i'm not sure about the error behavior. If we want to proceed with 
defaults in such a case, i would make this a warning and mention the 
used defaults.

> +
> +	/* Each unit in timeout register is 1/216,000,000 seconds */
> +	tmp64 = (u64)216000 * timeout_msec;
> +
> +	/* Clamp the requested value before writing it */
> +	timeout = tmp64 > 0xffffffff ? 0xffffffff : tmp64;
> +	timeout = timeout < 0xffff ? 0xffff : timeout;

Personally i'm not a huge fan of silently clamping wrong DT values.

Best regards

> +	writel(timeout, pcie->base + REG_OFFSET);
> +}
> +
>   static int brcm_pcie_start_link(struct brcm_pcie *pcie)
>   {
>   	struct device *dev = pcie->dev;
> @@ -1110,6 +1133,7 @@ static int brcm_pcie_start_link(struct brcm_pcie *pcie)
>   		return -ENODEV;
>   	}
>   
> +	brcm_config_completion_timeout(pcie);
>   	brcm_config_clkreq(pcie);
>   
>   	if (pcie->gen)

Re: [PATCH v1 3/3] PCI: brcmstb: Allow setting the completion timeout

Posted by Jim Quinlan 2 years, 8 months ago

On Thu, Apr 6, 2023 at 11:59 AM Stefan Wahren <stefan.wahren@i2se.com> wrote:
>
> Hi Jim,
>
> Am 06.04.23 um 14:46 schrieb Jim Quinlan:
> > Since the STB PCIe HW will cause a CPU abort on a completion timeout abort,
> > we might as well extend the timeout limit.  Further, different devices and
> > systems may requires a larger or smaller amount for L1SS exit.
> >
> > Signed-off-by: Jim Quinlan <jim2101024@gmail.com>
> > ---
> >   drivers/pci/controller/pcie-brcmstb.c | 24 ++++++++++++++++++++++++
> >   1 file changed, 24 insertions(+)
> >
> > diff --git a/drivers/pci/controller/pcie-brcmstb.c b/drivers/pci/controller/pcie-brcmstb.c
> > index 129eee7bdbc1..92d78f4dfaae 100644
> > --- a/drivers/pci/controller/pcie-brcmstb.c
> > +++ b/drivers/pci/controller/pcie-brcmstb.c
> > @@ -1080,6 +1080,29 @@ static void brcm_config_clkreq(struct brcm_pcie *pcie)
> >       writel(clkreq_set, pcie->base + PCIE_MISC_HARD_PCIE_HARD_DEBUG);
> >   }
> >
> > +static void brcm_config_completion_timeout(struct brcm_pcie *pcie)
> > +{
> > +     /* TIMEOUT register is two registers before RGR1_SW_INIT_1 */
> > +     const unsigned int REG_OFFSET = PCIE_RGR1_SW_INIT_1(pcie) - 8;
> > +     u32 timeout, timeout_msec = 1000;
> > +     u64 tmp64;
> > +     int ret;
> > +
> > +     ret = of_property_read_u32(pcie->np, "brcm,completion-abort-msecs",
> > +                                &timeout_msec);
> > +
> > +     if (ret && ret != -EINVAL)
> > +             dev_err(pcie->dev, "bad 'brcm,completion-abort-msecs' prop\n");
>
> i'm not sure about the error behavior. If we want to proceed with
> defaults in such a case, i would make this a warning and mention the
> used defaults.
Will do.

>
> > +
> > +     /* Each unit in timeout register is 1/216,000,000 seconds */
> > +     tmp64 = (u64)216000 * timeout_msec;
> > +
> > +     /* Clamp the requested value before writing it */
> > +     timeout = tmp64 > 0xffffffff ? 0xffffffff : tmp64;
> > +     timeout = timeout < 0xffff ? 0xffff : timeout;
>
> Personally i'm not a huge fan of silently clamping wrong DT values.
I will add a warning with limit info  on clamp and have the YAML min+max.

Thanks
Jim Quinlan
Broadcom STB
>
> Best regards
>
> > +     writel(timeout, pcie->base + REG_OFFSET);
> > +}
> > +
> >   static int brcm_pcie_start_link(struct brcm_pcie *pcie)
> >   {
> >       struct device *dev = pcie->dev;
> > @@ -1110,6 +1133,7 @@ static int brcm_pcie_start_link(struct brcm_pcie *pcie)
> >               return -ENODEV;
> >       }
> >
> > +     brcm_config_completion_timeout(pcie);
> >       brcm_config_clkreq(pcie);
> >
> >       if (pcie->gen)