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

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Date:   Mon, 31 May 2021 10:47:20 +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 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.
> 
> Signed-off-by: Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
> ---
> v2: new patch
>  drivers/net/can/spi/mcp251xfd/mcp251xfd-core.c | 9 +++++++--
>  1 file changed, 7 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/net/can/spi/mcp251xfd/mcp251xfd-core.c b/drivers/net/can/spi/mcp251xfd/mcp251xfd-core.c
> index e0ae00e34c7b..e42f87c3f2ec 100644
> --- a/drivers/net/can/spi/mcp251xfd/mcp251xfd-core.c
> +++ b/drivers/net/can/spi/mcp251xfd/mcp251xfd-core.c
> @@ -2856,7 +2856,7 @@ static int mcp251xfd_probe(struct spi_device *spi)
>  	struct gpio_desc *rx_int;
>  	struct regulator *reg_vdd, *reg_xceiver;
>  	struct clk *clk;
> -	u32 freq;
> +	u32 freq, rate;
>  	int err;
>  
>  	if (!spi->irq)
> @@ -2883,11 +2883,16 @@ static int mcp251xfd_probe(struct spi_device *spi)
>  		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....?

> +
> +	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. I've send a v3 to fix this.

>  
>  	/* Sanity check */
>  	if (freq < MCP251XFD_SYSCLOCK_HZ_MIN ||
> -- 
> 2.30.2
> 
>

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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