Re: [PATCH v10 4/5] wifi: brcmfmac: Add optional lpo clock enable support

[Arend van Spriel <arend.vanspriel@broadcom.com>]

On 8/14/2024 11:48 AM, Alexey Charkov wrote:
> On Wed, Aug 14, 2024 at 12:27 PM Jacobe Zang <jacobe.zang@wesion.com> wrote:
>>
>>
>>
>> On 2024/8/14 16:47, Alexey Charkov wrote:
>>> Hi Arend, Jacobe,
>>>
>>> On Tuesday, August 13, 2024 2:57:28 PM GMT+3 Arend van Spriel wrote:
>>>> On 8/13/2024 10:20 AM, Jacobe Zang wrote:
>>>>> WiFi modules often require 32kHz clock to function. Add support to
>>>>> enable the clock to PCIe driver and move "brcm,bcm4329-fmac" check
>>>>> to the top of brcmf_of_probe. Change function prototypes from void
>>>>> to int and add appropriate errno's for return values that will be
>>>>> send to bus when error occurred.
>>>>
>>>> I was going to say it looks good to me, but....
>>>>
>>>>> Co-developed-by: Ondrej Jirman <megi@xff.cz>
>>>>> Signed-off-by: Ondrej Jirman <megi@xff.cz>
>>>>> Co-developed-by: Arend van Spriel <arend.vanspriel@broadcom.com>
>>>>> Signed-off-by: Arend van Spriel <arend.vanspriel@broadcom.com>
>>>>> Reviewed-by: Sai Krishna <saikrishnag@marvell.com>
>>>>> Signed-off-by: Jacobe Zang <jacobe.zang@wesion.com>
>>>>> ---
>>>>>
>>>>>     .../broadcom/brcm80211/brcmfmac/bcmsdh.c      |  4 +-
>>>>>     .../broadcom/brcm80211/brcmfmac/common.c      |  3 +-
>>>>>     .../wireless/broadcom/brcm80211/brcmfmac/of.c | 53 +++++++++++--------
>>>>>     .../wireless/broadcom/brcm80211/brcmfmac/of.h |  9 ++--
>>>>>     .../broadcom/brcm80211/brcmfmac/pcie.c        |  3 ++
>>>>>     .../broadcom/brcm80211/brcmfmac/sdio.c        | 22 +++++---
>>>>>     .../broadcom/brcm80211/brcmfmac/usb.c         |  3 ++
>>>>>     7 files changed, 61 insertions(+), 36 deletions(-)
>>>>
>>>> [...]
>>>>
>>>>> diff --git a/drivers/net/wireless/broadcom/brcm80211/brcmfmac/of.c
>>>>> b/drivers/net/wireless/broadcom/brcm80211/brcmfmac/of.c index
>>>>> e406e11481a62..f19dc7355e0e8 100644
>>>>> --- a/drivers/net/wireless/broadcom/brcm80211/brcmfmac/of.c
>>>>> +++ b/drivers/net/wireless/broadcom/brcm80211/brcmfmac/of.c
>>>>
>>>> [...]
>>>>
>>>>> @@ -113,33 +118,39 @@ void brcmf_of_probe(struct device *dev, enum
>>>>> brcmf_bus_type bus_type,>
>>>>>              of_node_put(root);
>>>>>
>>>>>      }
>>>>>
>>>>> -   if (!np || !of_device_is_compatible(np, "brcm,bcm4329-fmac"))
>>>>> -           return;
>>>>> -
>>>>>
>>>>>      err = brcmf_of_get_country_codes(dev, settings);
>>>>>      if (err)
>>>>>
>>>>>              brcmf_err("failed to get OF country code map (err=%d)
>>> \n", err);
>>>>>
>>>>>      of_get_mac_address(np, settings->mac);
>>>>>
>>>>> -   if (bus_type != BRCMF_BUSTYPE_SDIO)
>>>>> -           return;
>>>>> +   if (bus_type == BRCMF_BUSTYPE_SDIO) {
>>>>
>>>> Don't like the fact that this now has an extra indentation level and it
>>>> offers no extra benefit. Just keep the original if-statement and return
>>>> 0. Consequently the LPO clock code should move just before the if-statement.
>>>>> +           if (of_property_read_u32(np, "brcm,drive-strength",
>>> &val) == 0)
>>>>> +                   sdio->drive_strength = val;
>>>>>
>>>>> -   if (of_property_read_u32(np, "brcm,drive-strength", &val) == 0)
>>>>> -           sdio->drive_strength = val;
>>>>> +           /* make sure there are interrupts defined in the node */
>>>>> +           if (!of_property_present(np, "interrupts"))
>>>>> +                   return 0;
>>>>>
>>>>> -   /* make sure there are interrupts defined in the node */
>>>>> -   if (!of_property_present(np, "interrupts"))
>>>>> -           return;
>>>>> +           irq = irq_of_parse_and_map(np, 0);
>>>>> +           if (!irq) {
>>>>> +                   brcmf_err("interrupt could not be
>>> mapped\n");
>>>>> +                   return 0;
>>>>> +           }
>>>>> +           irqf = irqd_get_trigger_type(irq_get_irq_data(irq));
>>>>> +
>>>>> +           sdio->oob_irq_supported = true;
>>>>> +           sdio->oob_irq_nr = irq;
>>>>> +           sdio->oob_irq_flags = irqf;
>>>>> +   }
>>>>>
>>>>> -   irq = irq_of_parse_and_map(np, 0);
>>>>> -   if (!irq) {
>>>>> -           brcmf_err("interrupt could not be mapped\n");
>>>>> -           return;
>>>>> +   clk = devm_clk_get_optional_enabled(dev, "lpo");
>>>>> +   if (!IS_ERR_OR_NULL(clk)) {
>>>>> +           brcmf_dbg(INFO, "enabling 32kHz clock\n");
>>>>> +           return clk_set_rate(clk, 32768);
>>>>> +   } else {
>>>>> +           return PTR_ERR_OR_ZERO(clk);
>>>>>
>>>>>      }
>>>>
>>>> Change this to:
>>>>    > +        clk = devm_clk_get_optional_enabled(dev, "lpo");
>>>>    > +        if (IS_ERR_OR_NULL(clk)) {
>>>>    > +                return PTR_ERR_OR_ZERO(clk);
>>>
>>> Perhaps in this case we should go for IS_ERR and PTR_ERR respectively.
>>> devm_clk_get_optional_enabled would return NULL when the optional clock is not
>>> found, so NULL is not an error state but serves as a dummy clock that can be> used with clk_set_rate.
>>
>> I think we don't need to set clock rate for clock is NULL. So it should
>> be changed to:
>>
>> +       clk = devm_clk_get_optional_enabled(dev, "lpo");
>> +       if (IS_ERR(clk)) {
>> +               return PTR_ERR(clk);
>> +       } else if (clk) {
>> +               brcmf_dbg(INFO, "enabling 32kHz clock\n");
>> +               clk_set_rate(clk, 32768);
>> +       }
> 
> If clk is NULL then clk_set_rate returns immediately with status zero,
> so there is little difference from whether you wrap it into another if
> (clk) or not. You can probably drop the debug statement altogether and
> call clk_set_rate unconditionally - this will look neater.

The construct above is indeed only needed to get the debug statement 
correct given the behavior of clk_set_rate(). However, for debugging it 
is useful to know that the LPO clock is defined and used or not. Maybe 
do this:

        clk = devm_clk_get_optional_enabled(dev, "lpo");
        if (IS_ERR(clk))
                return PTR_ERR(clk);

        brcmf_dbg(INFO, "%s LPO clock\n", clk ? "enable" : "no");
        clk_set_rate(clk, 32768);

Regards,
Arend

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