Re: [PATCH v2 21/66] media: sun6i-csi: Always set exclusive module clock rate

Paul Kocialkowski
2022-02-11T16:29:41Z

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Hi,

Thanks for the review,

On Mon 07 Feb 22, 10:14, Maxime Ripard wrote:
> On Sat, Feb 05, 2022 at 07:53:44PM +0100, Paul Kocialkowski wrote:
> > In some situations the default rate of the module clock is not the
> > required one for operation (for example when reconfiguring the clock
> > tree to use a different parent). As a result, always set the correct
> > rate for the clock (and take care of cleanup).
> >
> > Signed-off-by: Paul Kocialkowski <paul.kocialkowski@bootlin.com>
> > ---
> > .../platform/sunxi/sun6i-csi/sun6i_csi.c | 54 ++++++++++++++-----
> > 1 file changed, 41 insertions(+), 13 deletions(-)
> >
> > diff --git a/drivers/media/platform/sunxi/sun6i-csi/sun6i_csi.c b/drivers/media/platform/sunxi/sun6i-csi/sun6i_csi.c
> > index 8155e9560164..2355088fdc37 100644
> > --- a/drivers/media/platform/sunxi/sun6i-csi/sun6i_csi.c
> > +++ b/drivers/media/platform/sunxi/sun6i-csi/sun6i_csi.c
> > @@ -154,9 +154,6 @@ int sun6i_csi_set_power(struct sun6i_csi_device *csi_dev, bool enable)
> > regmap_update_bits(regmap, CSI_EN_REG, CSI_EN_CSI_EN, 0);
> >
> > clk_disable_unprepare(csi_dev->clk_ram);
> > - if (of_device_is_compatible(dev->of_node,
> > - "allwinner,sun50i-a64-csi"))
> > - clk_rate_exclusive_put(csi_dev->clk_mod);
> > clk_disable_unprepare(csi_dev->clk_mod);
> > reset_control_assert(csi_dev->reset);
> > return 0;
> > @@ -168,9 +165,6 @@ int sun6i_csi_set_power(struct sun6i_csi_device *csi_dev, bool enable)
> > return ret;
> > }
> >
> > - if (of_device_is_compatible(dev->of_node, "allwinner,sun50i-a64-csi"))
> > - clk_set_rate_exclusive(csi_dev->clk_mod, 300000000);
> > -
> > ret = clk_prepare_enable(csi_dev->clk_ram);
> > if (ret) {
> > dev_err(csi_dev->dev, "Enable clk_dram_csi clk err %d\n", ret);
> > @@ -190,8 +184,6 @@ int sun6i_csi_set_power(struct sun6i_csi_device *csi_dev, bool enable)
> > clk_ram_disable:
> > clk_disable_unprepare(csi_dev->clk_ram);
> > clk_mod_disable:
> > - if (of_device_is_compatible(dev->of_node, "allwinner,sun50i-a64-csi"))
> > - clk_rate_exclusive_put(csi_dev->clk_mod);
> > clk_disable_unprepare(csi_dev->clk_mod);
> > return ret;
> > }
> > @@ -819,6 +811,7 @@ static int sun6i_csi_resources_setup(struct sun6i_csi_device *csi_dev,
> > struct platform_device *platform_dev)
> > {
> > struct device *dev = csi_dev->dev;
> > + unsigned long clk_mod_rate;
> > void __iomem *io_base;
> > int ret;
> > int irq;
> > @@ -856,28 +849,53 @@ static int sun6i_csi_resources_setup(struct sun6i_csi_device *csi_dev,
> > return PTR_ERR(csi_dev->clk_ram);
> > }
> >
> > + if (of_device_is_compatible(dev->of_node, "allwinner,sun50i-a64-csi"))
> > + clk_mod_rate = 300000000;
> > + else
> > + clk_mod_rate = 297000000;
> > +
> > + ret = clk_set_rate_exclusive(csi_dev->clk_mod, clk_mod_rate);
> > + if (ret) {
> > + dev_err(dev, "failed to set mod clock rate\n");
> > + return ret;
> > + }
> > +
> > /* Reset */
> >
> > csi_dev->reset = devm_reset_control_get_shared(dev, NULL);
> > if (IS_ERR(csi_dev->reset)) {
> > dev_err(dev, "failed to acquire reset\n");
> > - return PTR_ERR(csi_dev->reset);
> > + ret = PTR_ERR(csi_dev->reset);
> > + goto error_clk_rate_exclusive;
> > }
> >
> > /* Interrupt */
> >
> > irq = platform_get_irq(platform_dev, 0);
> > - if (irq < 0)
> > - return -ENXIO;
> > + if (irq < 0) {
> > + dev_err(dev, "failed to get interrupt\n");
> > + ret = -ENXIO;
> > + goto error_clk_rate_exclusive;
> > + }
> >
> > ret = devm_request_irq(dev, irq, sun6i_csi_isr, 0, SUN6I_CSI_NAME,
> > csi_dev);
> > if (ret) {
> > dev_err(dev, "failed to request interrupt\n");
> > - return ret;
> > + goto error_clk_rate_exclusive;
> > }
> >
> > return 0;
> > +
> > +error_clk_rate_exclusive:
> > + clk_rate_exclusive_put(csi_dev->clk_mod);
> > +
> > + return ret;
> > +}
> > +
> > +static void sun6i_csi_resources_cleanup(struct sun6i_csi_device *csi_dev)
> > +{
> > + clk_rate_exclusive_put(csi_dev->clk_mod);
> > }
>
> If you're going to have that function anyway, let's use
> devm_add_action_or_reset, it'll simplify the rest of the patch.

Well, this will cause issues later on when adding runtime pm support to
sun6i_csi_resources_cleanup: then it will no longer be equivalent
to the error case label.

Also I feel like making the resources_cleanup call a devm action would not
help clarify the general flow of the driver, where the matching setup/cleanup
calls are ordered in probe/remove. The driver is quite big with various parts
and I'd rather have them behave in a coherent and similar way.

What do you think?

Paul

--
Paul Kocialkowski, Bootlin
Embedded Linux and kernel engineering
https://bootlin.com

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