[PATCH v2] mmc: sunxi: Fix NULL pointer reference on clk_delays

[icenowy at aosc.io]

在 2017-08-08 15:02，Chen-Yu Tsai 写道：
> Some SoCs do not support clk delays for MMC in the clock control unit.
> These include the old controllers in A10/A10s/A13/R8, and the new eMMC
> controller in A64. The config structure for these controllers do not
> specify clk_delays, but the check for this was replaced in commit
> b0600daebf31 ("mmc: sunxi: Support controllers that can use both old
> and new timings").
> 
> This patch adds back the check for clk_delays, and also adds comments
> for both checks in sunxi_mmc_clk_set_phase().
> 
> Fixes: b0600daebf31 ("mmc: sunxi: Support controllers that can use
> 		      both old and new timings")
> Signed-off-by: Chen-Yu Tsai <wens at csie.org>

Should I add a Tested-by here?

> ---
> This fixes an mmc regression on A10/A10s/A13/R8 and A64 introduced
> by the A83T mmc patches.
> 
> v1 was inlined in a reply to "mmc: sunxi: fix new timings mode on A64
> EMMC (MMC2) controller"
> 
> Changes since v1:
> 
>   - Polished comments
> 
> I've tested this on my A10 Cubieboard and A20 Cubieboard2.
> ---
>  drivers/mmc/host/sunxi-mmc.c | 5 +++++
>  1 file changed, 5 insertions(+)
> 
> diff --git a/drivers/mmc/host/sunxi-mmc.c 
> b/drivers/mmc/host/sunxi-mmc.c
> index 3777517982dd..9dc6d726ec49 100644
> --- a/drivers/mmc/host/sunxi-mmc.c
> +++ b/drivers/mmc/host/sunxi-mmc.c
> @@ -722,9 +722,14 @@ static int sunxi_mmc_clk_set_phase(struct
> sunxi_mmc_host *host,
>  {
>  	int index;
> 
> +	/* clk controller delays not used under new timings mode */
>  	if (host->use_new_timings)
>  		return 0;
> 
> +	/* some old controllers don't support delays */
> +	if (!host->cfg->clk_delays)
> +		return 0;
> +
>  	/* determine delays */
>  	if (rate <= 400000) {
>  		index = SDXC_CLK_400K;