linux-kernel - Re: [PATCH v1] i2c: designware: Add support to get I2C related timing parameters from firmware.

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Date:   Wed, 7 Sep 2022 19:26:22 +0300
From:   Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
To:     Sudarshan Ravula <sudarshan.ravula@...el.com>
Cc:     wsa@...nel.org, linux-i2c@...r.kernel.org,
        linux-kernel@...r.kernel.org, jarkko.nikula@...ux.intel.com,
        pandith.n@...el.com, lakshmi.sowjanya.d@...el.com
Subject: Re: [PATCH v1] i2c: designware: Add support to get I2C related
 timing parameters from firmware.

On Wed, Sep 07, 2022 at 09:39:20PM +0530, Sudarshan Ravula wrote:
> Similar to I2C designware platform driver add i2c_parse_fw_timings() in
> PCI driver, to get I2C related timing parameters from firmware.
> 
> Signed-off-by: Sudarshan Ravula <sudarshan.ravula@...el.com>
> Acked-by: Jarkko Nikula <jarkko.nikula@...ux.intel.com>
> Reviewed-by: Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
> ---
>  drivers/i2c/busses/i2c-designware-pcidrv.c | 5 ++++-
>  1 file changed, 4 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/i2c/busses/i2c-designware-pcidrv.c b/drivers/i2c/busses/i2c-designware-pcidrv.c
> index 608e61209455..c001719209be 100644
> --- a/drivers/i2c/busses/i2c-designware-pcidrv.c
> +++ b/drivers/i2c/busses/i2c-designware-pcidrv.c
> @@ -243,6 +243,7 @@ static int i2c_dw_pci_probe(struct pci_dev *pdev,
>  	int r;
>  	struct dw_pci_controller *controller;
>  	struct dw_scl_sda_cfg *cfg;
> +	struct i2c_timings *t;
>  
>  	if (id->driver_data >= ARRAY_SIZE(dw_pci_controllers))
>  		return dev_err_probe(&pdev->dev, -EINVAL,
> @@ -272,12 +273,14 @@ static int i2c_dw_pci_probe(struct pci_dev *pdev,
>  		return r;
>  
>  	dev->get_clk_rate_khz = controller->get_clk_rate_khz;
> -	dev->timings.bus_freq_hz = I2C_MAX_FAST_MODE_FREQ;
>  	dev->base = pcim_iomap_table(pdev)[0];
>  	dev->dev = &pdev->dev;
>  	dev->irq = pci_irq_vector(pdev, 0);
>  	dev->flags |= controller->flags;
>  
> +	t = &dev->timings;
> +	i2c_parse_fw_timings(&pdev->dev, t, false);

Note that this is safe to drop above assignment with 'false' given here since
i2c_dw_adjust_bus_speed(), which is called after, will set that default and if
nothing is read from firmware the value of bus_freq_hz will be 0 as guaranteed
by kzalloc().

> +
>  	pci_set_drvdata(pdev, dev);
>  
>  	if (controller->setup) {
> -- 
> 2.17.1
> 

-- 
With Best Regards,
Andy Shevchenko