Em Sun, 1 Feb 2015 12:12:33 +0100 (CET)
Guennadi Liakhovetski <g.liakhovetski@xxxxxx> escreveu:
> V4L2 clocks, e.g. used by camera sensors for their master clock, do not
> have to be supplied by a different V4L2 driver, they can also be
> supplied by an independent source. In this case the standart kernel
> clock API should be used to handle such clocks. This patch adds support
> for such cases.
>
> Signed-off-by: Guennadi Liakhovetski <g.liakhovetski@xxxxxx>
> Acked-by: Laurent Pinchart <laurent.pinchart@xxxxxxxxxxxxxxxx>
> ---
>
> v4: sizeof(*clk) :)
>
> drivers/media/v4l2-core/v4l2-clk.c | 48 +++++++++++++++++++++++++++++++++++---
> include/media/v4l2-clk.h | 2 ++
> 2 files changed, 47 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/media/v4l2-core/v4l2-clk.c b/drivers/media/v4l2-core/v4l2-clk.c
> index 3ff0b00..9f8cb20 100644
> --- a/drivers/media/v4l2-core/v4l2-clk.c
> +++ b/drivers/media/v4l2-core/v4l2-clk.c
> @@ -9,6 +9,7 @@
> */
>
> #include <linux/atomic.h>
> +#include <linux/clk.h>
> #include <linux/device.h>
> #include <linux/errno.h>
> #include <linux/list.h>
> @@ -37,6 +38,21 @@ static struct v4l2_clk *v4l2_clk_find(const char *dev_id)
> struct v4l2_clk *v4l2_clk_get(struct device *dev, const char *id)
> {
> struct v4l2_clk *clk;
> + struct clk *ccf_clk = clk_get(dev, id);
> +
> + if (PTR_ERR(ccf_clk) == -EPROBE_DEFER)
> + return ERR_PTR(-EPROBE_DEFER);
Why not do just:
return ccf_clk;
> +
> + if (!IS_ERR_OR_NULL(ccf_clk)) {
> + clk = kzalloc(sizeof(*clk), GFP_KERNEL);
> + if (!clk) {
> + clk_put(ccf_clk);
> + return ERR_PTR(-ENOMEM);
> + }
> + clk->clk = ccf_clk;
> +
> + return clk;
> + }
The error condition here looks a little weird to me. I mean, if the
CCF clock returns an error, shouldn't it fail instead of silently
run some logic to find another clock source? Isn't it risky on getting
a wrong value?
If the above code is right, please add a comment there explaining
why it is safe to discard the CCF clock error.
>
> mutex_lock(&clk_lock);
> clk = v4l2_clk_find(dev_name(dev));
> @@ -56,6 +72,12 @@ void v4l2_clk_put(struct v4l2_clk *clk)
> if (IS_ERR(clk))
> return;
>
> + if (clk->clk) {
> + clk_put(clk->clk);
> + kfree(clk);
> + return;
> + }
> +
> mutex_lock(&clk_lock);
>
> list_for_each_entry(tmp, &clk_list, list)
> @@ -93,8 +115,12 @@ static void v4l2_clk_unlock_driver(struct v4l2_clk *clk)
>
> int v4l2_clk_enable(struct v4l2_clk *clk)
> {
> - int ret = v4l2_clk_lock_driver(clk);
> + int ret;
>
> + if (clk->clk)
> + return clk_prepare_enable(clk->clk);
> +
> + ret = v4l2_clk_lock_driver(clk);
> if (ret < 0)
> return ret;
>
> @@ -120,6 +146,9 @@ void v4l2_clk_disable(struct v4l2_clk *clk)
> {
> int enable;
>
> + if (clk->clk)
> + return clk_disable_unprepare(clk->clk);
> +
> mutex_lock(&clk->lock);
>
> enable = --clk->enable;
> @@ -137,8 +166,12 @@ EXPORT_SYMBOL(v4l2_clk_disable);
>
> unsigned long v4l2_clk_get_rate(struct v4l2_clk *clk)
> {
> - int ret = v4l2_clk_lock_driver(clk);
> + int ret;
> +
> + if (clk->clk)
> + return clk_get_rate(clk->clk);
>
> + ret = v4l2_clk_lock_driver(clk);
> if (ret < 0)
> return ret;
>
> @@ -157,7 +190,16 @@ EXPORT_SYMBOL(v4l2_clk_get_rate);
>
> int v4l2_clk_set_rate(struct v4l2_clk *clk, unsigned long rate)
> {
> - int ret = v4l2_clk_lock_driver(clk);
> + int ret;
> +
> + if (clk->clk) {
> + long r = clk_round_rate(clk->clk, rate);
> + if (r < 0)
> + return r;
> + return clk_set_rate(clk->clk, r);
> + }
> +
> + ret = v4l2_clk_lock_driver(clk);
>
> if (ret < 0)
> return ret;
> diff --git a/include/media/v4l2-clk.h b/include/media/v4l2-clk.h
> index 928045f..3ef6e3d 100644
> --- a/include/media/v4l2-clk.h
> +++ b/include/media/v4l2-clk.h
> @@ -22,6 +22,7 @@
> struct module;
> struct device;
>
> +struct clk;
> struct v4l2_clk {
> struct list_head list;
> const struct v4l2_clk_ops *ops;
> @@ -29,6 +30,7 @@ struct v4l2_clk {
> int enable;
> struct mutex lock; /* Protect the enable count */
> atomic_t use_count;
> + struct clk *clk;
> void *priv;
> };
>
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