Re: [PATCH v2] mmc: dw_mmc: Don't start commands while busy

[Doug Anderson]

Javier,

On Mon, Feb 23, 2015 at 8:33 AM, Javier Martinez Canillas
<javier.martinez@xxxxxxxxxxxxxxx> wrote:
> Hello Doug,
>
> On 02/20/2015 09:31 PM, Doug Anderson wrote:
>> We've seen problems on some WiFi modules where we seem to send a CMD53
>> (which requires the data lines) while the module is asserting busy.
>> We shouldn't do that.
>>
>> The Designware Databook says that before issuing a new data transfer
>> command we should check for busy, so that's what we'll do.
>>
>
> I tried $subject along with patches:
>
> * mmc: dw_mmc: Make sure we only adjust the clock when power is on
>   https://patchwork.kernel.org/patch/5858261/
>
> * mmc: dw_mmc: Give a good reset after we give power
>   https://patchwork.kernel.org/patch/5858281/
>
> but unfortunately these don't solve the "Timeout sending command" error
> that I got when trying to enable the WiFi module on the Peach Pit and Pi:
>
> [    5.332103] dwmmc_exynos 12210000.mmc: Busy; trying anyway
> [    5.336110] mmc_host mmc2: Timeout sending command (cmd 0x202000 arg 0x0 status 0x0)
>
>> We'll leverage the existing dw_mmc knowledge about whether it should
>> wait for the previous command to finish to know whether we should
>> check for busy before sending the command.  This means we won't end up
>> incorrectly waiting for things like CMD52 (SDIO) or CMD13 (SD) which
>> don't use the data line.
>>
>> Note that this also has the advantage of making sure that we don't
>> change the clock while the card is busy, too.
>>
>
> The timeout happens in this case:
>
> mmc_rescan()
>         mmc_attach_sdio()
>                 mmc_sdio_init_card()
>                         dw_mci_init_card()
>                                 mci_send_cmd(slot, SDMMC_CMD_UPD_CLK |
>                                                    SDMMC_CMD_PRV_DAT_WAIT, 0);
>
> which should be covered by your patch since the SDMMC_CMD_PRV_DAT_WAIT flag
> is set but SDMMC_STATUS_BUSY bit is not cleared and mci_send_cmd() timeouts
> when sending the command to the controller.
>
>>
>> +static void dw_mci_wait_while_busy(struct dw_mci *host, u32 cmd_flags)
>> +{
>> +     unsigned long timeout = jiffies + msecs_to_jiffies(500);
>> +
>> +     /*
>> +      * Databook says that before issuing a new data transfer command
>> +      * we need to check to see if the card is busy.  Data transfer commands
>> +      * all have SDMMC_CMD_PRV_DAT_WAIT set, so we'll key off that.
>> +      *
>> +      * ...also allow sending for SDMMC_CMD_VOLT_SWITCH where busy is
>> +      * expected.
>> +      */
>> +     if ((cmd_flags & SDMMC_CMD_PRV_DAT_WAIT) &&
>> +         !(cmd_flags & SDMMC_CMD_VOLT_SWITCH)) {
>> +             while (mci_readl(host, STATUS) & SDMMC_STATUS_BUSY) {
>> +                     if (time_after(jiffies, timeout)) {
>> +                             /* Command will fail; we'll pass error then */
>> +                             dev_err(host->dev, "Busy; trying anyway\n");
>
> Addy's "mmc: dw_mmc: fix bug that cause 'Timeout sending command" [0] patch
> reset the controller if it was busy for more than 500ms while your patch
> doesn't. I don't mean that your patch is not correct, I'm just mentioning
> because calling dw_mci_ctrl_reset() does makes the command to succeed the
> next time and I can see the SDIO devices enumerated in /sys/bus/sdio/devices:
>
> [    5.892124] dwmmc_exynos 12210000.mmc: Busy; trying anyway
> [    5.892135] mmc_host mmc2: Timeout sending command (cmd 0x202000 arg 0x0 status 0x0)
> [    5.913885] mmc2: new high speed SDIO card at address 0001
> [    6.582133] dwmmc_exynos 12210000.mmc: Busy; trying anyway

Hmmmmm.  In the cases I was seeing I didn't need the "reset" since the
"SDMMC_CMD_UPD_CLK" was the one from dw_mci_set_ios() and my patch:

* mmc: dw_mmc: Give a good reset after we give power
  https://patchwork.kernel.org/patch/5858281/

...gave the needed reset after vqmmc power was applied.  Then dw_mmc
never got wedged and didn't need the reset to get it unwedged.  In
your care you're getting called from dw_mci_init_card().  That should
happen _after_ dw_mci_set_ios() as far as I know.  Can you put a
printout in the reset in dw_mci_set_ios() and make sure it runs?

How many resets do you need before things work?  If just one then
something must be happening between the initial "set_ios" and the
"init_card".  Any chance you could figure out what that is?  If it
needs multiple resets then it seems like something is fishy...


> but that reset may not be right since the WiFi chip does not work because
> the firmware later fails to load:
>
> [  240.273352] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
> [  240.281159] kworker/2:1     D c04b3340     0  1260      2 0x00000000
> [  240.287487] Workqueue: events request_firmware_work_func
> [  240.292763] [<c04b3340>] (__schedule) from [<c04b36f0>] (schedule+0x34/0x98)
> [  240.299815] [<c04b36f0>] (schedule) from [<c04b7198>] (schedule_timeout+0x120/0x16c)
> [  240.307537] [<c04b7198>] (schedule_timeout) from [<c04b41b4>] (wait_for_common+0xb0/0x154)
> [  240.315783] [<c04b41b4>] (wait_for_common) from [<c037abb8>] (mmc_wait_for_req+0xa0/0x140)
> [  240.324020] [<c037abb8>] (mmc_wait_for_req) from [<c0384b04>] (mmc_io_rw_extended+0x304/0x34c)
> [  240.332607] [<c0384b04>] (mmc_io_rw_extended) from [<c0385a90>] (sdio_io_rw_ext_helper+0x138/0x1a4)
> [  240.341630] [<c0385a90>] (sdio_io_rw_ext_helper) from [<c0385b1c>] (sdio_writesb+0x20/0x28)
> [  240.349962] [<c0385b1c>] (sdio_writesb) from [<c02e60d4>] (mwifiex_write_data_sync+0x4c/0x80)
> [  240.358460] [<c02e60d4>] (mwifiex_write_data_sync) from [<c02e68e4>] (mwifiex_prog_fw_w_helper+0x1b0/0x2c4)
> [  240.368176] [<c02e68e4>] (mwifiex_prog_fw_w_helper) from [<c02c7d6c>] (mwifiex_dnld_fw+0x58/0x10c)
> [  240.377127] [<c02c7d6c>] (mwifiex_dnld_fw) from [<c02c5f10>] (mwifiex_fw_dpc+0x264/0x408)
> [  240.385263] [<c02c5f10>] (mwifiex_fw_dpc) from [<c0291b28>] (request_firmware_work_func+0x30/0x50)
> [  240.394200] [<c0291b28>] (request_firmware_work_func) from [<c0032ae8>] (process_one_work+0x120/0x324)
> [  240.403482] [<c0032ae8>] (process_one_work) from [<c0032e58>] (worker_thread+0x138/0x464)
> [  240.411635] [<c0032e58>] (worker_thread) from [<c0037470>] (kthread+0xd8/0xf4)
> [  240.418837] [<c0037470>] (kthread) from [<c000e680>] (ret_from_fork+0x14/0x34)
>
> The DTS changes on top of linux-next to add WiFi support is [1] in case you can
> find something that is wrong with my patch.

I still haven't had time to try using the new MMC power sequencing :(
so I can't say for sure, but one thought below...


> I also checked that the external reference clock for the WiFi module is enabled
> correctly according to /sys/kernel/debug/clk/clk_summary and also by looking
> at the value in the max77802 i2c register address that enables that clock.
>
> Any hints will be highly appreciated.
>
> Thanks a lot and best regards,
> Javier
>
> [0]: https://lkml.org/lkml/2015/2/5/222
> [1]:
> From ced0974472d109019e1ee551a6dd08f16ae5cfc2 Mon Sep 17 00:00:00 2001
> From: Javier Martinez Canillas <javier.martinez@xxxxxxxxxxxxxxx>
> Date: Mon, 23 Feb 2014 15:42:15 +0100
> Subject: [PATCH] ARM: dts: Add Peach Pit board WiFi support
>
> Peach boards have an SDIO WiFi module that is always powered but it
> needs a power sequence involving the reset and enable pins and also
> a 32kHz reference clock.
>
> Add a dev node for the SDIO slot and the MMC power sequence provider.
>
> Signed-off-by: Javier Martinez Canillas <javier.martinez@xxxxxxxxxxxxxxx>
> ---
>  arch/arm/boot/dts/exynos5420-peach-pit.dts | 59 ++++++++++++++++++++++++++++++
>  1 file changed, 59 insertions(+)
>
> diff --git a/arch/arm/boot/dts/exynos5420-peach-pit.dts b/arch/arm/boot/dts/exynos5420-peach-pit.dts
> index ec86d9523935..26df041e46e7 100644
> --- a/arch/arm/boot/dts/exynos5420-peach-pit.dts
> +++ b/arch/arm/boot/dts/exynos5420-peach-pit.dts
> @@ -125,6 +125,14 @@
>                         };
>                 };
>         };
> +
> +       mmc1_pwrseq: mmc1_pwrseq {
> +               compatible = "mmc-pwrseq-simple";
> +               reset-gpios = <&gpx0 1 GPIO_ACTIVE_LOW>, /* WIFI_RSTn */
> +                             <&gpx0 0 GPIO_ACTIVE_LOW>; /* WIFI_EN */

Any chance you want "WIFI_EN" to actually be specified as "vmmc" for
the slot?  ...possibly with a 'regulator-enable-ramp-delay' specified?
 I know that with SD Cards on an rk3288 board I needed to make sure
there was a bit of delay after "vqmmc" came up...

BTW: IIRC the "WIFI_RSTn" ended up being totally unused.  It was used
in earlier revs of the board that had a different rev of the WiFi
chip...

> +               clocks = <&max77802 MAX77802_CLK_32K_CP>;
> +               clock-names = "ext_clock";
> +       };
>  };
>
>  &adc {
> @@ -691,6 +699,24 @@
>         bus-width = <8>;
>  };
>
> +&mmc_1 {
> +       status = "okay";
> +       num-slots = <1>;
> +       broken-cd;
> +       cap-sdio-irq;
> +       card-detect-delay = <200>;
> +       clock-frequency = <400000000>;
> +       samsung,dw-mshc-ciu-div = <1>;
> +       samsung,dw-mshc-sdr-timing = <0 1>;

Just for kicks, does this help if you do:

ciu-div = 3
sdr-timing = 2 3

...I know we have ciu-div = 1 downstream, but we also have tuning...

> +       samsung,dw-mshc-ddr-timing = <0 2>;
> +       pinctrl-names = "default";
> +       pinctrl-0 = <&sd1_clk>, <&sd1_cmd>, <&sd1_int>, <&sd1_bus4>,
> +                   <&sd1_bus8>, <&wifi_en>, <&wifi_rst>;
> +       bus-width = <4>;
> +       cap-sd-highspeed;
> +       mmc-pwrseq = <&mmc1_pwrseq>;

Should you be specifying a "vqmmc-supply" here?  I know that we don't
change voltages for WiFi (starts at 1.8V and ends up at 1.8V) but
still might be good to specify it...

> +};
> +
>  &mmc_2 {
>         status = "okay";
>         num-slots = <1>;
> @@ -710,6 +736,20 @@
>         pinctrl-names = "default";
>         pinctrl-0 = <&mask_tpm_reset>;
>
> +       wifi_en: wifi-en {
> +               samsung,pins = "gpx0-0";
> +               samsung,pin-function = <1>;
> +               samsung,pin-pud = <0>;
> +               samsung,pin-drv = <0>;
> +       };
> +
> +       wifi_rst: wifi-rst {
> +               samsung,pins = "gpx0-1";
> +               samsung,pin-function = <1>;
> +               samsung,pin-pud = <0>;
> +               samsung,pin-drv = <0>;
> +       };
> +
>         max98090_irq: max98090-irq {
>                 samsung,pins = "gpx0-2";
>                 samsung,pin-function = <0>;
> @@ -797,6 +837,25 @@
>         };
>  };
>
> +&pinctrl_1 {
> +       /* Adjust WiFi drive strengths lower for EMI */
> +       sd1_clk: sd1-clk {
> +               samsung,pin-drv = <2>;
> +       };
> +
> +       sd1_cmd: sd1-cmd {
> +               samsung,pin-drv = <2>;
> +       };
> +
> +       sd1_bus4: sd1-bus-width4 {
> +               samsung,pin-drv = <2>;
> +       };
> +
> +       sd1_bus8: sd1-bus-width8 {
> +               samsung,pin-drv = <2>;
> +       };
> +};
> +
>  &pinctrl_2 {
>         pmic_dvs_2: pmic-dvs-2 {
>                 samsung,pins = "gpj4-2";
> --
> 2.1.3
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