Re: [PATCH v2 1/2] clk: at91: Added more information logging.
From: Boris Brezillon
Date: Tue Apr 10 2018 - 04:24:16 EST
Hi Marcin,
On Mon, 9 Apr 2018 20:16:21 -0400
Marcin Ziemianowicz <marcin@xxxxxxxxxxxxxxxx> wrote:
> I noticed that when debugging some USB clocking issue that there weren't
> many ways to tell what the state of the USB clocking system was. This
> adds a few logging statements to see what the relevant code is trying to
> do.
>
> Signed-off-by: Marcin Ziemianowicz <marcin@xxxxxxxxxxxxxxxx>
> ---
> drivers/clk/at91/clk-pll.c | 6 +++++-
> drivers/clk/at91/clk-usb.c | 10 ++++++++--
> drivers/usb/host/ohci-at91.c | 16 ++++++++++------
This should be split in 2 patches (one adding traces to clk drivers and
another doing it for the USB host driver), so that those patches can be
merged independently by the clk and usb maintainers.
> 3 files changed, 23 insertions(+), 9 deletions(-)
>
> diff --git a/drivers/clk/at91/clk-pll.c b/drivers/clk/at91/clk-pll.c
> index 7d3223fc7161..534961766ae5 100644
> --- a/drivers/clk/at91/clk-pll.c
> +++ b/drivers/clk/at91/clk-pll.c
> @@ -133,6 +133,7 @@ static unsigned long clk_pll_recalc_rate(struct clk_hw *hw,
> {
> struct clk_pll *pll = to_clk_pll(hw);
> unsigned int pllr;
> + unsigned long recalcedrate;
Just name it 'rate' or 'realrate'.
> u16 mul;
> u8 div;
>
> @@ -144,7 +145,10 @@ static unsigned long clk_pll_recalc_rate(struct clk_hw *hw,
> if (!div || !mul)
> return 0;
>
> - return (parent_rate / div) * (mul + 1);
> + recalcedrate = (parent_rate / div) * (mul + 1);
> + pr_debug("clk-pll: calculating new rate, (%lu hz / %u) * %u = %lu hz\n",
If the prefix is alway "clk-pll: " you could define pr_fmt() to add it
to all your pr_xxx() messages.
BTW, it's not about calculating the new rate, but retrieving the
actual rate.
> + parent_rate, div, mul, recalcedrate);
Add an empty line here.
> + return recalcedrate;
> }
>
> static long clk_pll_get_best_div_mul(struct clk_pll *pll, unsigned long rate,
> diff --git a/drivers/clk/at91/clk-usb.c b/drivers/clk/at91/clk-usb.c
> index 791770a563fc..2fa877e99bac 100644
> --- a/drivers/clk/at91/clk-usb.c
> +++ b/drivers/clk/at91/clk-usb.c
> @@ -48,11 +48,15 @@ static unsigned long at91sam9x5_clk_usb_recalc_rate(struct clk_hw *hw,
> struct at91sam9x5_clk_usb *usb = to_at91sam9x5_clk_usb(hw);
> unsigned int usbr;
> u8 usbdiv;
> + unsigned int calcdclock;
Ditto: s/calcdclock/realrate/, and make it unsigned long.
>
> regmap_read(usb->regmap, AT91_PMC_USB, &usbr);
> usbdiv = (usbr & AT91_PMC_OHCIUSBDIV) >> SAM9X5_USB_DIV_SHIFT;
>
> - return DIV_ROUND_CLOSEST(parent_rate, (usbdiv + 1));
> + calcdclock = DIV_ROUND_CLOSEST(parent_rate, (usbdiv + 1));
> + pr_debug("clk-usb: calculating new rate, %lu hz / %u = %u hz\n",
> + parent_rate, usbdiv + 1, calcdclock);
Empty line here too.
> + return calcdclock;
> }
>
> static int at91sam9x5_clk_usb_determine_rate(struct clk_hw *hw,
> @@ -98,7 +102,6 @@ static int at91sam9x5_clk_usb_determine_rate(struct clk_hw *hw,
> if (!best_diff)
> break;
> }
> -
> if (best_rate < 0)
> return best_rate;
>
> @@ -142,6 +145,9 @@ static int at91sam9x5_clk_usb_set_rate(struct clk_hw *hw, unsigned long rate,
> if (div > SAM9X5_USB_MAX_DIV + 1 || !div)
> return -EINVAL;
>
> + pr_debug("clk-usb: setting USB clock divider to %lu hz / %lu = %lu hz\n",
The formulation is weird. Maybe you should just remove 'divider' here:
"setting USB clock to %lu hz / %lu = %lu hz"
> + parent_rate, div, rate);
> +
> regmap_update_bits(usb->regmap, AT91_PMC_USB, AT91_PMC_OHCIUSBDIV,
> (div - 1) << SAM9X5_USB_DIV_SHIFT);
>
> diff --git a/drivers/usb/host/ohci-at91.c b/drivers/usb/host/ohci-at91.c
> index 5ad9e9bdc8ee..c57a239918f9 100644
> --- a/drivers/usb/host/ohci-at91.c
> +++ b/drivers/usb/host/ohci-at91.c
> @@ -70,11 +70,13 @@ static const struct ohci_driver_overrides ohci_at91_drv_overrides __initconst =
>
> /*-------------------------------------------------------------------------*/
>
> -static void at91_start_clock(struct ohci_at91_priv *ohci_at91)
> +static void at91_start_clock(struct ohci_at91_priv *ohci_at91,
> + struct device *dev)
Maybe you could just pass a pdev or dev pointer and let the function
extract the ohci_at91 object with:
struct usb_hcd *hcd = platform_get_drvdata(pdev);
struct ohci_at91_priv *ohci_at91 = hcd_to_ohci_at91_priv(hcd);
> {
> if (ohci_at91->clocked)
> return;
>
> + dev_dbg(dev, "Enabling hclk, iclk, and setting fclk to 48 Mhz\n");
Add an empty line here.
> clk_set_rate(ohci_at91->fclk, 48000000);
> clk_prepare_enable(ohci_at91->hclk);
> clk_prepare_enable(ohci_at91->iclk);
> @@ -82,11 +84,13 @@ static void at91_start_clock(struct ohci_at91_priv *ohci_at91)
> ohci_at91->clocked = true;
> }
>
> -static void at91_stop_clock(struct ohci_at91_priv *ohci_at91)
> +static void at91_stop_clock(struct ohci_at91_priv *ohci_at91,
> + struct device *dev)
> {
> if (!ohci_at91->clocked)
> return;
>
> + dev_dbg(dev, "Disabling hclk, iclk, and fclk\n");
> clk_disable_unprepare(ohci_at91->fclk);
> clk_disable_unprepare(ohci_at91->iclk);
> clk_disable_unprepare(ohci_at91->hclk);
> @@ -104,7 +108,7 @@ static void at91_start_hc(struct platform_device *pdev)
> /*
> * Start the USB clocks.
> */
> - at91_start_clock(ohci_at91);
> + at91_start_clock(ohci_at91, &pdev->dev);
>
> /*
> * The USB host controller must remain in reset.
> @@ -128,7 +132,7 @@ static void at91_stop_hc(struct platform_device *pdev)
> /*
> * Stop the USB clocks.
> */
> - at91_stop_clock(ohci_at91);
> + at91_stop_clock(ohci_at91, &pdev->dev);
> }
>
>
> @@ -623,7 +627,7 @@ ohci_hcd_at91_drv_suspend(struct device *dev)
>
> /* flush the writes */
> (void) ohci_readl (ohci, &ohci->regs->control);
> - at91_stop_clock(ohci_at91);
> + at91_stop_clock(ohci_at91, dev);
> }
>
> return ret;
> @@ -638,7 +642,7 @@ ohci_hcd_at91_drv_resume(struct device *dev)
> if (ohci_at91->wakeup)
> disable_irq_wake(hcd->irq);
>
> - at91_start_clock(ohci_at91);
> + at91_start_clock(ohci_at91, dev);
>
> ohci_resume(hcd, false);
>
Regards,
Boris