Re: [PATCH] arm64: dts: rockchip: Fix rk3399-gru-* s2r (pinctrl hogs, wifi reset)

[Marc Zyngier]

Hi Doug,

On 06/03/18 18:00, Doug Anderson wrote:
> Hi,
> 
> On Tue, Mar 6, 2018 at 3:58 AM, Marc Zyngier <marc.zyngier@xxxxxxx> wrote:
>> Hi all,
>>
>> On 01/03/18 08:43, Heiko StÃbner wrote:
>>> Am Dienstag, 27. Februar 2018, 21:47:11 CET schrieb Douglas Anderson:
>>>> Back in the early days when gru devices were still under development
>>>> we found an issue where the WiFi reset line needed to be configured as
>>>> early as possible during the boot process to avoid the WiFi module
>>>> being in a bad state.
>>>>
>>>> We found that the way to get the kernel to do this in the earliest
>>>> possible place was to configure this line in the pinctrl hogs, so
>>>> that's what we did.  For some history here you can see
>>>> <http://crosreview.com/368770>.  After the time that change landed in
>>>> the kernel, we landed a firmware change to configure this line even
>>>> earlier.  See <http://crosreview.com/399919>.  However, even after the
>>>> firmware change landed we kept the kernel change to deal with the fact
>>>> that some people working on devices might take a little while to
>>>> update their firmware.
>>>>
>>>> At this there are definitely zero devices out in the wild that have
>>>> firmware without the fix in it.  Specifically looking in the firmware
>>>> branch several critically important fixes for memory stability landed
>>>> after the patch in coreboot and I know we didn't ship without those.
>>>> Thus, by now, everyone should have the new firmware and it's safe to
>>>> not have the kernel set this up in a pinctrl hog.
>>>>
>>>> Historically, even though it wasn't needed to have this in a pinctrl
>>>> hog, we still kept it since it didn't hurt.  Pinctrl would apply the
>>>> default hog at bootup and then would never touch things again.  That
>>>> all changed with commit 981ed1bfbc6c ("pinctrl: Really force states
>>>> during suspend/resume").  After that commit then we'll re-apply the
>>>> default hog at resume time and that can screw up the reset state of
>>>> WiFi.  ...and on rk3399 if you touch a device on PCIe in the wrong way
>>>> then the whole system can go haywire.  That's what was happening.
>>>> Specifically you'd resume a rk3399-gru-* device and it would mostly
>>>> resume, then would crash with some crazy weird crash.
>>>>
>>>> One could say, perhaps, that the recent pinctrl change was at fault
>>>> (and should be fixed) since it changed behavior.  ...but that's not
>>>> really true.  The device tree for rk3399-gru is really to blame.
>>>> Specifically since the pinctrl is defined in the hog and not in the
>>>> "wlan-pd-n" node then the actual user of this pin doesn't have a
>>>> pinctrl entry for it.  That's bad.
>>>>
>>>> Let's fix our problems by just moving the control of
>>>> "wlan_module_reset_l pinctrl" out of the hog and put them in the
>>>> proper place.
>>>>
>>>> NOTE: in theory, I think it should actually be possible to have a pin
>>>> controlled _both_ by the hog and by an actual device.  Once the device
>>>> claims the pin I think the hog is supposed to let go.  I'm not 100%
>>>> sure that this works and in any case this solution would be more
>>>> complex than is necessary.
>>>>
>>>> Reported-by: Marc Zyngier <marc.zyngier@xxxxxxx>
>>>> Fixes: 48f4d9796d99 ("arm64: dts: rockchip: add Gru/Kevin DTS")
>>>> Fixes: 981ed1bfbc6c ("pinctrl: Really force states during suspend/resume")
>>>> Signed-off-by: Douglas Anderson <dianders@xxxxxxxxxxxx>
>>>
>>> applied as fix for 4.16 with the 2 Tested-tags
>> Sorry to rain on everyone's parade, but further testing shows that this
>> patch may not be enough to restore a reliable s2r. My initial testing
>> did show that we were resuming without the VOP errors, but there seem to
>> be further issues (I'm loosing the keyboard and the trackpad after
>> resume on Kevin).
>>
>> Applying my initial hack makes it work again. I suspect that there are
>> more hog pins that need tweaking, but I'm a bit out of my depth here.
> 
> Are you positive you weren't just wearing your lucky hat when you
> tested your patch and then took it off when you tested mine?  As far

So far, I seem to have a 100% success rate in resuming with my silly
hack, whist your DT patch alone only gives me a 50% rate at best.

> as I can see the only hogs left on kevin are:
> 
>   &ap_pwroff      /* AP will auto-assert this when in S3 */
>   &clk_32k        /* This pin is always 32k on gru boards */
> 
> Those map to:
> 
>   ap_pwroff: ap-pwroff {
>      rockchip,pins = <1 5 RK_FUNC_1 &pcfg_pull_none>;
>   };
> 
>   clk_32k: clk-32k {
>     rockchip,pins = <0 0 RK_FUNC_2 &pcfg_pull_none>;
>   };
> 
> So I added some printouts at suspend/resume time.  Specifically I set
> a boolean to "true" for the duration rockchip_pinctrl_suspend() and
> rockchip_pinctrl_resume() and this turned on a printout in
> rockchip_set_mux().  My printout looked like this (yeah, I know it's a
> whitespace-damaged patch just to show what I'm doing):
> 
> +       regmap_read(regmap, reg, &before);
>         data = (mask << (bit + 16));
>         rmask = data | (data >> 16);
>         data |= (mux & mask) << bit;
>         ret = regmap_update_bits(regmap, reg, rmask, data);
> 
> +       regmap_read(regmap, reg, &after);
> +
> +       if (DOUG) {
> +               dev_info(info->dev,
> +                        "setting mux of GPIO%d-%d to %d; %#010x=>%#010x\n",
> +                        bank->bank_num, pin, mux, reg, before, after);
> +       }
> 
> ...and a similar one in rockchip_set_pull().  That showed this at resume time:
> 
> [   62.284427] rockchip-pinctrl pinctrl: setting mux of GPIO1-5 to 1;
> 0x00009400=>0x00009400
> [   62.294423] rockchip-pinctrl pinctrl: setting pull of GPIO1-5;
> 0x000041aa=>0x000041aa
> [   62.303343] rockchip-pinctrl pinctrl: setting mux of GPIO0-0 to 2;
> 0x00005002=>0x00005002
> [   62.313240] rockchip-pinctrl pinctrl: setting pull of GPIO0-0;
> 0x00000ddc=>0x00000ddc
> [
> 
> Said another way: pinmux and pull isn't actually changing due to the
> hogs.  We can see if something else could be changing, but I'd really
> want to be sure you're certain that the hogs are causing you
> problems...

I cannot say for sure that the hogs are the issue. But I thought that
they were the only pins affected by 981ed1bfbc6c... If this patch can
affect other pins, then I'm probably barking up the wrong tree.

Thanks,

	M.
-- 
Jazz is not dead. It just smells funny...