On 1/24/22 6:07 PM, Sean Anderson wrote:
> On 1/24/22 5:44 PM, Thinh Nguyen wrote:
>> Sean Anderson wrote:
>>> This property allows setting the reference clock frequency properly for
>>> ACPI-based systems. It is not documented under dt-bindings, since it is
>>> not intended for use on DT-based systems. DT-based systems should use
>>> the clocks property instead.
>>>
>>> Frequency is preferred over period since it has greater precision when
>>> used in calculations.
>>>
>>> Signed-off-by: Sean Anderson <sean.anderson@xxxxxxxx>
>>> ---
>>>
>>> Changes in v2:
>>> - New
>>>
>>> drivers/usb/dwc3/core.c | 6 ++++--
>>> drivers/usb/dwc3/core.h | 4 +++-
>>> 2 files changed, 7 insertions(+), 3 deletions(-)
>>>
>>> diff --git a/drivers/usb/dwc3/core.c b/drivers/usb/dwc3/core.c
>>> index 883e119377f0..5f3dc5f6cbcb 100644
>>> --- a/drivers/usb/dwc3/core.c
>>> +++ b/drivers/usb/dwc3/core.c
>>> @@ -350,8 +350,8 @@ static void dwc3_ref_clk_period(struct dwc3 *dwc)
>>> u32 reg;
>>> unsigned long decr, fladj, rate, period;
>>>
>>> - if (dwc->ref_clk) {
>>> - rate = clk_get_rate(dwc->ref_clk);
>>> + if (dwc->ref_clk || dwc->ref_clk_freq) {
>>> + rate = clk_get_rate(dwc->ref_clk) ?: dwc->ref_clk_freq;
>>> if (!rate)
>>> return;
>>> period = NSEC_PER_SEC / rate;
>>> @@ -1492,6 +1492,8 @@ static void dwc3_get_properties(struct dwc3 *dwc)
>>> &dwc->fladj);
>>> device_property_read_u32(dev, "snps,ref-clock-period-ns",
>>> &dwc->ref_clk_per);
>>> + device_property_read_u32(dev, "snps,ref-clock-frequency-hz",
>>> + &dwc->ref_clk_freq);
>>
>> Please also document in dwc3 DT file whenever we add a new property.
>
> This is intentionally undocumented, as noted in the commit message.
> Rob Herring has said that dt-bindings should only document properties
> intended for device-tree.
context: https://lore.kernel.org/all/20181219202734.GA31178@bogus/
This patch was later resubmitted as 24bc6e68efa0 ("serial: sc16is7xx:
Respect clock-frequency property") without the dt-bindings documentation.
+CC Rob if he wants to comment on this specific situation.
--Sean
