linux-kernel - Re: [PATCH v2 1/2] can: mcp251xfd: Try to get crystal clock rate from property

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Date:   Mon, 31 May 2021 12:03:14 +0200
From:   Marc Kleine-Budde <mkl@...gutronix.de>
To:     Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
Cc:     linux-can@...r.kernel.org, netdev@...r.kernel.org,
        linux-kernel@...r.kernel.org,
        Manivannan Sadhasivam <mani@...nel.org>,
        Thomas Kopp <thomas.kopp@...rochip.com>,
        Wolfgang Grandegger <wg@...ndegger.com>,
        "David S. Miller" <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>
Subject: Re: [PATCH v2 1/2] can: mcp251xfd: Try to get crystal clock rate
 from property

On 31.05.2021 12:58:29, Andy Shevchenko wrote:
> On Mon, May 31, 2021 at 10:47:20AM +0200, Marc Kleine-Budde wrote:
> > On 26.05.2021 22:33:26, Andy Shevchenko wrote:
> > > In some configurations, mainly ACPI-based, the clock frequency of the device
> > > is supplied by very well established 'clock-frequency' property. Hence, try
> > > to get it from the property at last if no other providers are available.
> 
> > >  		return dev_err_probe(&spi->dev, PTR_ERR(reg_xceiver),
> > >  				     "Failed to get Transceiver regulator!\n");
> > >  
> > > -	clk = devm_clk_get(&spi->dev, NULL);
> > > +	/* Always ask for fixed clock rate from a property. */
> > > +	device_property_read_u32(&spi->dev, "clock-frequency", &rate);
> > 
> > what about error handling....?
> 
> Not needed, but rate should be assigned to 0, which is missed.
> 
> > > +	clk = devm_clk_get_optional(&spi->dev, NULL);
> > >  	if (IS_ERR(clk))
> > >  		return dev_err_probe(&spi->dev, PTR_ERR(clk),
> > >  				     "Failed to get Oscillator (clock)!\n");
> > >  	freq = clk_get_rate(clk);
> > > +	if (freq == 0)
> > > +		freq = rate;
> > 
> > ... this means we don't fail if there is neither a clk nor a
> > clock-frequency property.
> 
> The following will check for it (which is already in the code)
> 
>   if (freq <= MCP251XFD_SYSCLOCK_HZ_MAX / MCP251XFD_OSC_PLL_MULTIPLIER) {

Good point.

> > I've send a v3 to fix this.
> 
> You mean I have to send v3?
> Sure!

I have send a v3, see:

https://lore.kernel.org/r/20210531084444.1785397-1-mkl@pengutronix.de

Marc

-- 
Pengutronix e.K.                 | Marc Kleine-Budde           |
Embedded Linux                   | https://www.pengutronix.de  |
Vertretung West/Dortmund         | Phone: +49-231-2826-924     |
Amtsgericht Hildesheim, HRA 2686 | Fax:   +49-5121-206917-5555 |

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