Re: [PATCH v2 1/8] clk: imx: add common logic to detect early UART usage

["Uwe Kleine-König" <u.kleine-koenig@pengutronix.de>]

Hello Lucas,

On Fri, Sep 04, 2015 at 06:00:12PM +0200, Lucas Stach wrote:
> Both earlycon and eralyprintk depend on the bootloader setup UART
> clocks being retained. This patch adds the common logic to detect such
> situations and make the information available to the clock drivers, as
> well as adding the facilities to disable those clocks at the end of
> the kernel init.
> 
> Signed-off-by: Lucas Stach <l.stach@pengutronix.de>
> ---
>  drivers/clk/imx/clk.c | 46 ++++++++++++++++++++++++++++++++++++++++++++++
>  drivers/clk/imx/clk.h |  1 +
>  2 files changed, 47 insertions(+)
> 
> diff --git a/drivers/clk/imx/clk.c b/drivers/clk/imx/clk.c
> index df12b5307175..3357e29e43ab 100644
> --- a/drivers/clk/imx/clk.c
> +++ b/drivers/clk/imx/clk.c
> @@ -73,3 +73,49 @@ void imx_cscmr1_fixup(u32 *val)
>  	*val ^= CSCMR1_FIXUP;
>  	return;
>  }
> +
> +static int __initdata imx_keep_uart_clocks;
> +static struct clk __initdata ***imx_uart_clocks;
> +
> +static int __init imx_keep_uart_clocks_param(char *str)
> +{
> +	imx_keep_uart_clocks = 1;
> +
> +	return 0;
> +}
> +__setup_param("earlycon", imx_keep_uart_earlycon,
> +	      imx_keep_uart_clocks_param, 0);
> +__setup_param("earlyprintk", imx_keep_uart_earlyprintk,
> +	      imx_keep_uart_clocks_param, 0);
> +
> +void __init imx_register_uart_clocks(struct clk **clks[])

const struct clk **clks[]?

I wonder why you need an array of pointers to pointers of clocks. Isn't
one indirection less possible and more easy?

> +{
> +	if (imx_keep_uart_clocks) {
> +		int i;
> +
> +		imx_uart_clocks = clks;
> +		for (i = 0;; i++) {
> +			if (imx_uart_clocks[i])
> +				clk_prepare_enable(*imx_uart_clocks[i]);
> +			else
> +				break;
> +		}

I would have written this as:

	for (i = 0; imx_uart_clocks[i]; ++i)
		clk_prepare_enable(*imx_uart_clocks[i]);

but I guess that's a matter of taste.

Best regards
Uwe

-- 
Pengutronix e.K.                           | Uwe Kleine-König            |
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