[PATCH] usb: host: ohci-generic: Make usage of clock/reset bulk() API
Fabrice Gasnier
fabrice.gasnier at foss.st.com
Mon Sep 4 11:25:06 CEST 2023
On 9/2/23 11:06, Xavier Drudis Ferran wrote:
> Is the change of behaviour intended when a clock or reset is not found ?
> (see below)
Hi Xavier,
I'd say yes, although I haven't seen that... please find my answers below.
>
> El Wed, Aug 30, 2023 at 10:01:49AM +0200, Fabrice Gasnier deia:
>> Make usage of clock and reset bulk API in order to simplify the code
>>
>> Signed-off-by: Fabrice Gasnier <fabrice.gasnier at foss.st.com>
>> ---
>>
>> drivers/usb/host/ohci-generic.c | 92 +++++++++++----------------------
>> 1 file changed, 29 insertions(+), 63 deletions(-)
>>
>> diff --git a/drivers/usb/host/ohci-generic.c b/drivers/usb/host/ohci-generic.c
>> index 2d8d38ce9a40..95aa608d8c19 100644
>> --- a/drivers/usb/host/ohci-generic.c
>> +++ b/drivers/usb/host/ohci-generic.c
>> @@ -16,75 +16,41 @@
>>
>> struct generic_ohci {
>> ohci_t ohci;
>> - struct clk *clocks; /* clock list */
>> - struct reset_ctl *resets; /* reset list */
>> + struct clk_bulk clocks; /* clock list */
>> + struct reset_ctl_bulk resets; /* reset list */
>> struct phy phy;
>> - int clock_count; /* number of clock in clock list */
>> - int reset_count; /* number of reset in reset list */
>> };
>>
>> static int ohci_usb_probe(struct udevice *dev)
>> {
>> struct ohci_regs *regs = dev_read_addr_ptr(dev);
>> struct generic_ohci *priv = dev_get_priv(dev);
>> - int i, err, ret, clock_nb, reset_nb;
>> -
>> - err = 0;
>> - priv->clock_count = 0;
>> - clock_nb = dev_count_phandle_with_args(dev, "clocks", "#clock-cells",
>> - 0);
>> - if (clock_nb > 0) {
>> - priv->clocks = devm_kcalloc(dev, clock_nb, sizeof(struct clk),
>> - GFP_KERNEL);
>> - if (!priv->clocks)
>> - return -ENOMEM;
>> -
>> - for (i = 0; i < clock_nb; i++) {
>> - err = clk_get_by_index(dev, i, &priv->clocks[i]);
>> - if (err < 0)
>> - break;
>> -
>
> Please note the old code was tolerant of not finding some clocks. It
> ignored any clock not found and any other listed after it in the
> "clocks" property and enabled the clocks before it.
>
> The clk_get_bulk() function instead returns an error when any clock in
> "clocks" is not found and releases (disables again and frees) those
> before it.
>
> I'm not aware of any case that breaks because of this, but I once saw
> a case of ehci not working and ohci working because one of the listed
> clocks not being found (ehci called clk_get_bulk(),
> clk_enable_blk()).
IMHO, the OHCI should have failed too in this example, instead of
silently ignoring the error. Hopefully it has probed.
The clk_get_bulk() code does a similar job compared to ohci current
code. It counts all clock entries. So, when trying to get them, these
should be found.
Having a clock listed, but it can't be found or taken rather looks like
a real error, that needs to be fixed.
(e.g. missing config for a clk/reset controller ? Or could it be a bug
in such a driver ? Or a miss-configured device-tree ? something else?)
Ignoring such error may be miss-leading (as you pointed out, one was
working).
I hope I don't miss your point. If this is the case, could you point
more precise example, or how it used to fail ?
> In that case, a fix by ignoring the missing clock
> in ehci was rejected, so maybe that criteria applies here as well and
> your patch is deemed correct. I don't know. That case won't break now,
> I think, either with or without your patch, because after another fix,
> that clock will be found.
If I understand correctly, this used to fixed elsewhere (e.g. there used
to be a real bug fixed) ?
> But I don't know if there might be similar
> cases.
>
> I just wanted to point out the change in behaviour. If the change is
> intended, then all is fine.
IMHO, this should be fine. I hope you agree with this change and the
rationale.
Best Regards,
Fabrice
>
>> - err = clk_enable(&priv->clocks[i]);
>> - if (err && err != -ENOSYS) {
>> - dev_err(dev, "failed to enable clock %d\n", i);
>> - clk_free(&priv->clocks[i]);
>> - goto clk_err;
>> - }
>> - priv->clock_count++;
>> - }
>> - } else if (clock_nb != -ENOENT) {
>> - dev_err(dev, "failed to get clock phandle(%d)\n", clock_nb);
>> - return clock_nb;
>> + int err, ret;
>> +
>> + ret = clk_get_bulk(dev, &priv->clocks);
>> + if (ret && ret != -ENOENT) {
>> + dev_err(dev, "Failed to get clocks (ret=%d)\n", ret);
>> + return ret;
>> + }
>> +
>> + err = clk_enable_bulk(&priv->clocks);
>> + if (err) {
>> + dev_err(dev, "Failed to enable clocks (err=%d)\n", err);
>> + goto clk_err;
>> }
>>
>> - priv->reset_count = 0;
>> - reset_nb = dev_count_phandle_with_args(dev, "resets", "#reset-cells",
>> - 0);
>> - if (reset_nb > 0) {
>> - priv->resets = devm_kcalloc(dev, reset_nb,
>> - sizeof(struct reset_ctl),
>> - GFP_KERNEL);
>> - if (!priv->resets)
>> - return -ENOMEM;
>> -
>> - for (i = 0; i < reset_nb; i++) {
>> - err = reset_get_by_index(dev, i, &priv->resets[i]);
>> - if (err < 0)
>> - break;
>> -
>
> Similar here.
>
>> - err = reset_deassert(&priv->resets[i]);
>> - if (err) {
>> - dev_err(dev, "failed to deassert reset %d\n", i);
>> - reset_free(&priv->resets[i]);
>> - goto reset_err;
>> - }
>> - priv->reset_count++;
>> - }
>> - } else if (reset_nb != -ENOENT) {
>> - dev_err(dev, "failed to get reset phandle(%d)\n", reset_nb);
>> + err = reset_get_bulk(dev, &priv->resets);
>> + if (err && err != -ENOENT) {
>> + dev_err(dev, "failed to get resets (err=%d)\n", err);
>> goto clk_err;
>> }
>>
>> + err = reset_deassert_bulk(&priv->resets);
>> + if (err) {
>> + dev_err(dev, "failed to get deassert resets (err=%d)\n", err);
>> + goto reset_err;
>> + }
>> +
>> err = generic_setup_phy(dev, &priv->phy, 0);
>> if (err)
>> goto reset_err;
>> @@ -101,13 +67,13 @@ phy_err:
>> dev_err(dev, "failed to shutdown usb phy\n");
>>
>> reset_err:
>> - ret = reset_release_all(priv->resets, priv->reset_count);
>> + ret = reset_release_bulk(&priv->resets);
>> if (ret)
>> - dev_err(dev, "failed to assert all resets\n");
>> + dev_err(dev, "failed to release resets (ret=%d)\n", ret);
>> clk_err:
>> - ret = clk_release_all(priv->clocks, priv->clock_count);
>> + ret = clk_release_bulk(&priv->clocks);
>> if (ret)
>> - dev_err(dev, "failed to disable all clocks\n");
>> + dev_err(dev, "failed to release clocks (ret=%d)\n", ret);
>>
>> return err;
>> }
>> @@ -125,11 +91,11 @@ static int ohci_usb_remove(struct udevice *dev)
>> if (ret)
>> return ret;
>>
>> - ret = reset_release_all(priv->resets, priv->reset_count);
>> + ret = reset_release_bulk(&priv->resets);
>> if (ret)
>> return ret;
>>
>> - return clk_release_all(priv->clocks, priv->clock_count);
>> + return clk_release_bulk(&priv->clocks);
>> }
>>
>> static const struct udevice_id ohci_usb_ids[] = {
>> --
>> 2.25.1
>>
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