netdev - RE: [PATCH net-next v7 3/9] net: txgbe: Register fixed rate clock

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Date: Wed, 10 May 2023 14:47:50 +0800
From: Jiawen Wu <jiawenwu@...stnetic.com>
To: "'Simon Horman'" <simon.horman@...igine.com>
Cc: <netdev@...r.kernel.org>,
	<jarkko.nikula@...ux.intel.com>,
	<andriy.shevchenko@...ux.intel.com>,
	<mika.westerberg@...ux.intel.com>,
	<jsd@...ihalf.com>,
	<Jose.Abreu@...opsys.com>,
	<andrew@...n.ch>,
	<hkallweit1@...il.com>,
	<linux@...linux.org.uk>,
	<linux-i2c@...r.kernel.org>,
	<linux-gpio@...r.kernel.org>,
	<mengyuanlou@...-swift.com>
Subject: RE: [PATCH net-next v7 3/9] net: txgbe: Register fixed rate clock

On Tuesday, May 9, 2023 11:32 PM, Simon Horman wrote:
> On Tue, May 09, 2023 at 10:27:28AM +0800, Jiawen Wu wrote:
> > In order for I2C to be able to work in standard mode, register a fixed
> > rate clock for each I2C device.
> >
> > Signed-off-by: Jiawen Wu <jiawenwu@...stnetic.com>
> 
> ...
> 
> > @@ -70,6 +72,32 @@ static int txgbe_swnodes_register(struct txgbe *txgbe)
> >  	return software_node_register_node_group(nodes->group);
> >  }
> >
> > +static int txgbe_clock_register(struct txgbe *txgbe) {
> > +	struct pci_dev *pdev = txgbe->wx->pdev;
> > +	struct clk_lookup *clock;
> > +	char clk_name[32];
> > +	struct clk *clk;
> > +
> > +	snprintf(clk_name, sizeof(clk_name), "i2c_designware.%d",
> > +		 (pdev->bus->number << 8) | pdev->devfn);
> > +
> > +	clk = clk_register_fixed_rate(NULL, clk_name, NULL, 0, 156250000);
> > +	if (IS_ERR(clk))
> > +		return PTR_ERR(clk);
> > +
> > +	clock = clkdev_create(clk, NULL, clk_name);
> > +	if (!clock) {
> > +		clk_unregister(clk);
> > +		return PTR_ERR(clock);
> 
> Hi Jiawen,
> 
> Sorry for missing this earlier, but the above error handling doesn't seem right.
> 
>    * This error condition is met if clock == NULL
>    * So the above is returning PTR_ERR(NULL), which is a yellow flag to me.
>      In any case, PTR_ERR(NULL) => 0 is returned on error.
>    * The caller treats a 0 return value as success.
> 
>    Perhaps this should be: return -ENOMEM?

No problem, I will fix it in patch v8.

> 
> > +	}
> > +
> > +	txgbe->clk = clk;
> > +	txgbe->clock = clock;
> > +
> > +	return 0;
> > +}
> > +
> >  int txgbe_init_phy(struct txgbe *txgbe)  {
> >  	int ret;
> > @@ -80,10 +108,23 @@ int txgbe_init_phy(struct txgbe *txgbe)
> >  		return ret;
> >  	}
> >
> > +	ret = txgbe_clock_register(txgbe);
> > +	if (ret) {
> > +		wx_err(txgbe->wx, "failed to register clock: %d\n", ret);
> > +		goto err_unregister_swnode;
> > +	}
> > +
> >  	return 0;
> 
> ...
>