Re: [PATCH v6 4/5] wifi: brcmfmac: Add optional lpo clock enable support

[Arend van Spriel]

On 7/31/2024 2:01 PM, Alexey Charkov wrote:
> On Wed, Jul 31, 2024 at 2:15 PM Arend van Spriel
> <arend.vanspriel@xxxxxxxxxxxx> wrote:
> > On 7/31/2024 12:16 PM, Alexey Charkov wrote:
> > > Hi Jacobe,
> > >
> > >
> > > On 31/07/2024 9:11 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
> > >   >
> > >   > Co-developed-by: Ondrej Jirman <megi@xxxxxx>
> > >   > Signed-off-by: Ondrej Jirman <megi@xxxxxx>
> > >   > Signed-off-by: Jacobe Zang <jacobe.zang@xxxxxxxxxx>
> > >   > ---
> > >   >  .../net/wireless/broadcom/brcm80211/brcmfmac/of.c    | 12 +++++++++++-
> > >   >  1 file changed, 11 insertions(+), 1 deletion(-)
> > >   >
> > >   > diff --git a/drivers/net/wireless/broadcom/brcm80211/brcmfmac/of.c
> > > b/drivers/net/wireless/broadcom/brcm80211/brcmfmac/of.c
> > >   > index e406e11481a62..7e0a2ad5c7c8a 100644
> > >   > --- a/drivers/net/wireless/broadcom/brcm80211/brcmfmac/of.c
> > >   > +++ b/drivers/net/wireless/broadcom/brcm80211/brcmfmac/of.c
> > >   > @@ -6,6 +6,7 @@
> > >   >  #include <linux/of.h>
> > >   >  #include <linux/of_irq.h>
> > >   >  #include <linux/of_net.h>
> > >   > +#include <linux/clk.h>
> > >   >
> > >   >  #include <defs.h>
> > >   >  #include "debug.h"
> > >   > @@ -70,12 +71,16 @@ void brcmf_of_probe(struct device *dev, enum
> > > brcmf_bus_type bus_type,
> > >   >  {
> > >   >      struct brcmfmac_sdio_pd *sdio = &settings->bus.sdio;
> > >   >      struct device_node *root, *np = dev->of_node;
> > >   > +    struct clk *clk;
> > >   >      const char *prop;
> > >   >      int irq;
> > >   >      int err;
> > >   >      u32 irqf;
> > >   >      u32 val;
> > >   >
> > >   > +    if (!np || !of_device_is_compatible(np, "brcm,bcm4329-fmac"))
> > >   > +        return;
> > >
> > > Did you test this? The DTS patch you sent as part of this series doesn't
> > > list "brcm,bcm4329-fmac" in the compatible, so this will probably return
> > > right here, skipping over the rest of your patch.
> > >
> > > Please test before resending, both with and without the driver for the
> > > Bluetooth part of the chip (since it also touches clocks).
> > >
> > > You are also changing the behavior for other systems by putting this
> > > check further up the probe path, which might break things for no reason.
> > > Better put your clk-related addition below where this check was
> > > originally, rather than reorder stuff you don't have to reorder.
> >
> > That was upon my suggestion. That check was originally at the top of the
> > function, but people added stuff before that. I agree that makes the
> > compatible "brcm,brcm4329-fmac" required which is what the textual
> > binding stated before the switch to YAML was made:
> >
> > """
> > Broadcom BCM43xx Fullmac wireless SDIO devices
> >
> > This node provides properties for controlling the Broadcom wireless
> > device. The
> > node is expected to be specified as a child node to the SDIO controller that
> > connects the device to the system.
> >
> > Required properties:
> >
> >    - compatible : Should be "brcm,bcm4329-fmac".
> > """
> >
> > Not sure whether this is still true for YAML version (poor YAML reading
> > skills ;-) ), but it should as the switch from textual to YAML should
> > not have changed the bindings specification.
> >
> > >   > +
> > >   >      /* Apple ARM64 platforms have their own idea of board type,
> > > passed in
> > >   >       * via the device tree. They also have an antenna SKU parameter
> > >   >       */
> > >   > @@ -113,8 +118,13 @@ 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"))
> > >   > +    clk = devm_clk_get_optional_enabled(dev, "lpo");
> > >   > +    if (!IS_ERR_OR_NULL(clk)) {
> > >   > +        brcmf_dbg(INFO, "enabling 32kHz clock\n");
> > >   > +        clk_set_rate(clk, 32768);
> > >   > +    } else {
> > >   >          return;
> > >
> > > Why return here? If the clock is optional, a lot of systems will not
> > > have it - that shouldn't prevent the driver from probing. And you are
> > > still not handling the -EPROBE_DEFER case which was mentioned on your
> > > previous submission.
> >
> > Right. The else statement above could/should be:
> >
> > } else if (clk && PTR_ERR(clk) == -EPROBE_DEFER) {
> >           return PTR_ERR(clk);
> > }
>
> ... plus change the function prototype to return int and propagate
> that error code through brcmf_get_module_param to brcmf_pcie_probe's
> return value. I guess checking clk for NULL is also redundant in this
> case?

Only wanted to give the suggestion to get started. Propagating the 
return value seemed obvious to me, but you are absolutely right. 
PTR_ERR(NULL) will probably be something else than -EPROBE_DEFER but it 
seems odd to me. Maybe PTR_ERR_OR_ZERO(clk) is a better option here.

Regards,
Arend