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

[Chen-Yu Tsai]

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@xxxxxxxx>
---
 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..020547e5fa45 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;
 
+	/* No need to set clk controller delays under new timings */
 	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;
-- 
2.13.3

<---

Separately we should ask what is the proper set of config flags that
describes the A64 EMMC controller.

Regards
ChenYu

> 
> Fix this issue by adding this variable and setting it to true in
> the configuration struct.
> 
> Fixes: 4fb3ce07eafa ("mmc: sunxi: Add EMMC (MMC2) controller compatible")
> 
> Signed-off-by: Icenowy Zheng <icenowy@xxxxxxx>
> ---
>  drivers/mmc/host/sunxi-mmc.c | 1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/drivers/mmc/host/sunxi-mmc.c b/drivers/mmc/host/sunxi-mmc.c
> index 59aba93beffb..4ad643e37014 100644
> --- a/drivers/mmc/host/sunxi-mmc.c
> +++ b/drivers/mmc/host/sunxi-mmc.c
> @@ -1142,6 +1142,7 @@ static const struct sunxi_mmc_cfg sun50i_a64_emmc_cfg = {
>  	.idma_des_size_bits = 13,
>  	.clk_delays = NULL,
>  	.can_calibrate = true,
> +	.needs_new_timings = true,
>  };
>  
>  static const struct of_device_id sunxi_mmc_of_match[] = {
> -- 
> 2.13.0
> 
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