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SubjectRe: [linux-sunxi] [PATCH 2/2] mmc: sunxi: fix new timings mode on A64 EMMC (MMC2) controller
在 2017-08-06 10:39,Chen-Yu Tsai 写道:
> On Sat, Aug 05, 2017 at 05:35:55AM +0800, Icenowy Zheng wrote:
>> The configuration struct of A64 EMMC(MMC2) compatible used to
>> have the needs_new_timings variable missing, which lead to NULL
>> pointer dereference now when trying to set up the old timings mode, as
>> the old timings mode doesn't exist at all on A64.
>
> I'm not familiar with the A64's eMMC controller. The datasheet says
> it does not have the timing switch register. It does not say whether
> it is always in the old or new timing mode. "needs_new_timings"
> probably meant that the switch has to be set.
>
> This fix doesn't really fix the underlying issue, which is the check
> for clk_delays was incorrectly replaced. sun4i/sun5i is also broken.
>
> Could you try this patch instead:
>
> <---
>
> From 23b841a11294cb6a0cf1e146616b068f60c2ec7d Mon Sep 17 00:00:00 2001
> From: Chen-Yu Tsai <wens@csie.org>
> Date: Sun, 6 Aug 2017 10:24:47 +0800
> Subject: [PATCH] mmc: sunxi: Fix NULL pointer reference on clk_delays
>
> 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@csie.org>

Successfully tested on A64 (SoPine with baseboard and eMMC module).

> ---
> 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@aosc.io>
>> ---
>> 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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>
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