Hi,
On Tue, Nov 5, 2024 at 8:18 AM Jiasheng Jiang
<jiashengjiangcool@xxxxxxxxx> wrote:
>
> Add check for the return value of clk_enable() in order to catch the
> potential exception. Moreover, convert the return type of
> rk3x_i2c_adapt_div() into int and add the check.
>
> Signed-off-by: Jiasheng Jiang <jiashengjiangcool@xxxxxxxxx>
> ---
> Changelog:
>
> v1 -> v2:
>
> 1. Remove the Fixes tag.
> 2. Use dev_err_probe to simplify error handling.
> ---
> drivers/i2c/busses/i2c-rk3x.c | 51 +++++++++++++++++++++++++----------
> 1 file changed, 37 insertions(+), 14 deletions(-)
Wow, this is a whole lot of code to add to check for an error that
can't really happen as far as I'm aware. Turning on a clock is just
some MMIO writes and can't fail, right? Is this really worth it? Maybe
just wrap clk_enable() and spam an error to the logs if it fails? If
we ever see that error we can figure out what's going on and if
there's a sensible reason it could fail we could add the more complex
code.
> @@ -883,7 +883,9 @@ static void rk3x_i2c_adapt_div(struct rk3x_i2c *i2c, unsigned long clk_rate)
> ret = i2c->soc_data->calc_timings(clk_rate, t, &calc);
> WARN_ONCE(ret != 0, "Could not reach SCL freq %u", t->bus_freq_hz);
>
> - clk_enable(i2c->pclk);
> + ret = clk_enable(i2c->pclk);
> + if (ret)
> + return dev_err_probe(i2c->dev, ret, "Can't enable bus clk for rk3399: %d\n", ret);
Officially you're only supposed to use "dev_err_probe()" from probe or
calls indirectly called from probe. You're now using it in a whole lot
of other places.
...also note that dev_err_probe() already prints the error so you
don't need to include it in your error message.
> @@ -942,19 +946,27 @@ static int rk3x_i2c_clk_notifier_cb(struct notifier_block *nb, unsigned long
> return NOTIFY_STOP;
>
> /* scale up */
> - if (ndata->new_rate > ndata->old_rate)
> - rk3x_i2c_adapt_div(i2c, ndata->new_rate);
> + if (ndata->new_rate > ndata->old_rate) {
> + if (rk3x_i2c_adapt_div(i2c, ndata->new_rate))
> + return NOTIFY_STOP;
> + }
>
> return NOTIFY_OK;
> case POST_RATE_CHANGE:
> /* scale down */
> - if (ndata->new_rate < ndata->old_rate)
> - rk3x_i2c_adapt_div(i2c, ndata->new_rate);
> + if (ndata->new_rate < ndata->old_rate) {
> + if (rk3x_i2c_adapt_div(i2c, ndata->new_rate))
> + return NOTIFY_STOP;
> + }
> +
> return NOTIFY_OK;
> case ABORT_RATE_CHANGE:
> /* scale up */
> - if (ndata->new_rate > ndata->old_rate)
> - rk3x_i2c_adapt_div(i2c, ndata->old_rate);
> + if (ndata->new_rate > ndata->old_rate) {
> + if (rk3x_i2c_adapt_div(i2c, ndata->old_rate))
> + return NOTIFY_STOP;
I'm not convinced you can actually return NODIFY_STOP from the
POST_RATE_CHANGE or ABORT_RATE_CHANGE. Have you confirmed that is
actually sensible?
> @@ -1365,9 +1385,12 @@ static int rk3x_i2c_probe(struct platform_device *pdev)
> }
>
> clk_rate = clk_get_rate(i2c->clk);
> - rk3x_i2c_adapt_div(i2c, clk_rate);
> + ret = rk3x_i2c_adapt_div(i2c, clk_rate);
> clk_disable(i2c->clk);
>
> + if (ret)
> + goto err_clk_notifier;
This one seems especially comical to add since the only way
rk3x_i2c_adapt_div() could fail would be if a nested clk_enable()
failed. ...and I'm 99% sure that's not possible.
-Doug
