linux-kernel - Re: [PATCH v4 18/23] ata: libahci_platform: Add function returning a clock-handle by id

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Date:   Thu, 16 Jun 2022 00:24:43 +0300
From:   Serge Semin <fancer.lancer@...il.com>
To:     Damien Le Moal <damien.lemoal@...nsource.wdc.com>
Cc:     Serge Semin <Sergey.Semin@...kalelectronics.ru>,
        Hans de Goede <hdegoede@...hat.com>,
        Jens Axboe <axboe@...nel.dk>, Hannes Reinecke <hare@...e.de>,
        Alexey Malahov <Alexey.Malahov@...kalelectronics.ru>,
        Pavel Parkhomenko <Pavel.Parkhomenko@...kalelectronics.ru>,
        Rob Herring <robh+dt@...nel.org>, linux-ide@...r.kernel.org,
        linux-kernel@...r.kernel.org, devicetree@...r.kernel.org
Subject: Re: [PATCH v4 18/23] ata: libahci_platform: Add function returning a
 clock-handle by id

On Tue, Jun 14, 2022 at 05:45:35PM +0900, Damien Le Moal wrote:
> On 6/10/22 17:17, Serge Semin wrote:
> > Since all the clocks are retrieved by the method
> > ahci_platform_get_resources() there is no need for the LLD (glue) drivers
> > to be looking for some particular of them in the kernel clocks table
> > again. Instead we suggest to add a simple method returning a
> > device-specific clock with passed connection ID if it is managed to be
> > found. Otherwise the function will return NULL. Thus the glue-drivers
> > won't need to either manually touching the hpriv->clks array or calling
> > clk_get()-friends. The AHCI platform drivers will be able to use the new
> > function right after the ahci_platform_get_resources() method invocation
> > and up to the device removal.
> > 
> > Note the method is left unused here, but will be utilized in the framework
> > of the DWC AHCI SATA driver being added in the next commit.
> > 
> > Signed-off-by: Serge Semin <Sergey.Semin@...kalelectronics.ru>
> > 
> > ---
> > 
> > Changelog v2:
> > - Fix some grammar mistakes in the method description.
> > 
> > Changelog v4:
> > - Add a note regarding the new method usage.
> > ---
> >  drivers/ata/libahci_platform.c | 27 +++++++++++++++++++++++++++
> >  include/linux/ahci_platform.h  |  3 +++
> >  2 files changed, 30 insertions(+)
> > 
> > diff --git a/drivers/ata/libahci_platform.c b/drivers/ata/libahci_platform.c
> > index 8b542a8bc487..418961f954af 100644
> > --- a/drivers/ata/libahci_platform.c
> > +++ b/drivers/ata/libahci_platform.c
> > @@ -95,6 +95,33 @@ void ahci_platform_disable_phys(struct ahci_host_priv *hpriv)
> >  }
> >  EXPORT_SYMBOL_GPL(ahci_platform_disable_phys);
> >  
> > +/**
> > + * ahci_platform_find_clk - Find platform clock
> > + * @hpriv: host private area to store config values
> > + * @con_id: clock connection ID
> > + *
> > + * This function returns a pointer to the clock descriptor of the clock with
> > + * the passed ID.
> > + *
> > + * RETURNS:
> > + * Pointer to the clock descriptor on success otherwise NULL
> > + */
> > +struct clk *ahci_platform_find_clk(struct ahci_host_priv *hpriv, const char *con_id)
> > +{
> > +	struct clk *clk = NULL;
> > +	int i;
> > +
> > +	for (i = 0; i < hpriv->n_clks; i++) {
> > +		if (!strcmp(hpriv->clks[i].id, con_id)) {
> > +			clk = hpriv->clks[i].clk;
> 
> 			return hpriv->clks[i].clk;
> 
> > +			break;
> > +		}
> > +	}
> > +
> > +	return clk;
> 

> And then "return NULL;" here and you do not need the clk variable.

Ok.

> 
> > +}
> > +EXPORT_SYMBOL_GPL(ahci_platform_find_clk);
> > +
> >  /**
> >   * ahci_platform_enable_clks - Enable platform clocks
> >   * @hpriv: host private area to store config values
> > diff --git a/include/linux/ahci_platform.h b/include/linux/ahci_platform.h
> > index 6d7dd472d370..3418980b0341 100644
> > --- a/include/linux/ahci_platform.h
> > +++ b/include/linux/ahci_platform.h
> > @@ -13,6 +13,7 @@
> >  
> >  #include <linux/compiler.h>
> >  
> > +struct clk;
> >  struct device;
> >  struct ata_port_info;
> >  struct ahci_host_priv;
> > @@ -21,6 +22,8 @@ struct scsi_host_template;
> >  
> >  int ahci_platform_enable_phys(struct ahci_host_priv *hpriv);
> >  void ahci_platform_disable_phys(struct ahci_host_priv *hpriv);
> > +struct clk *
> > +ahci_platform_find_clk(struct ahci_host_priv *hpriv, const char *con_id);
> 

> Please make this:
> 
> struct clk *ahci_platform_find_clk(struct ahci_host_priv *hpriv,
> 
>                                    const char *con_id);

Ok.

-Sergey

> 
> >  int ahci_platform_enable_clks(struct ahci_host_priv *hpriv);
> >  void ahci_platform_disable_clks(struct ahci_host_priv *hpriv);
> >  int ahci_platform_deassert_rsts(struct ahci_host_priv *hpriv);
> 
> 
> -- 
> Damien Le Moal
> Western Digital Research