linux-kernel - Re: [PATCH] pmdomain: imx: gpcv2: Adjust delay after power up handshake

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Message-ID: <CAPDyKFrm8wv7uFAumx5d6uMhr=LLUT8_RsQhNMF4DyOUe7uMFg@mail.gmail.com>
Date: Mon, 2 Dec 2024 17:12:10 +0100
From: Ulf Hansson <ulf.hansson@...aro.org>
To: Shengjiu Wang <shengjiu.wang@....com>
Cc: shawnguo@...nel.org, s.hauer@...gutronix.de, kernel@...gutronix.de, 
	festevam@...il.com, linux-pm@...r.kernel.org, imx@...ts.linux.dev, 
	linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org, 
	shengjiu.wang@...il.com, francesco@...cini.it
Subject: Re: [PATCH] pmdomain: imx: gpcv2: Adjust delay after power up handshake

On Thu, 21 Nov 2024 at 08:53, Shengjiu Wang <shengjiu.wang@....com> wrote:
>
> The udelay(5) is not enough, sometimes below kernel panic
> still be triggered:
>
> [    4.012973] Kernel panic - not syncing: Asynchronous SError Interrupt
> [    4.012976] CPU: 2 UID: 0 PID: 186 Comm: (udev-worker) Not tainted 6.12.0-rc2-0.0.0-devel-00004-g8b1b79e88956 #1
> [    4.012982] Hardware name: Toradex Verdin iMX8M Plus WB on Dahlia Board (DT)
> [    4.012985] Call trace:
> [...]
> [    4.013029]  arm64_serror_panic+0x64/0x70
> [    4.013034]  do_serror+0x3c/0x70
> [    4.013039]  el1h_64_error_handler+0x30/0x54
> [    4.013046]  el1h_64_error+0x64/0x68
> [    4.013050]  clk_imx8mp_audiomix_runtime_resume+0x38/0x48
> [    4.013059]  __genpd_runtime_resume+0x30/0x80
> [    4.013066]  genpd_runtime_resume+0x114/0x29c
> [    4.013073]  __rpm_callback+0x48/0x1e0
> [    4.013079]  rpm_callback+0x68/0x80
> [    4.013084]  rpm_resume+0x3bc/0x6a0
> [    4.013089]  __pm_runtime_resume+0x50/0x9c
> [    4.013095]  pm_runtime_get_suppliers+0x60/0x8c
> [    4.013101]  __driver_probe_device+0x4c/0x14c
> [    4.013108]  driver_probe_device+0x3c/0x120
> [    4.013114]  __driver_attach+0xc4/0x200
> [    4.013119]  bus_for_each_dev+0x7c/0xe0
> [    4.013125]  driver_attach+0x24/0x30
> [    4.013130]  bus_add_driver+0x110/0x240
> [    4.013135]  driver_register+0x68/0x124
> [    4.013142]  __platform_driver_register+0x24/0x30
> [    4.013149]  sdma_driver_init+0x20/0x1000 [imx_sdma]
> [    4.013163]  do_one_initcall+0x60/0x1e0
> [    4.013168]  do_init_module+0x5c/0x21c
> [    4.013175]  load_module+0x1a98/0x205c
> [    4.013181]  init_module_from_file+0x88/0xd4
> [    4.013187]  __arm64_sys_finit_module+0x258/0x350
> [    4.013194]  invoke_syscall.constprop.0+0x50/0xe0
> [    4.013202]  do_el0_svc+0xa8/0xe0
> [    4.013208]  el0_svc+0x3c/0x140
> [    4.013215]  el0t_64_sync_handler+0x120/0x12c
> [    4.013222]  el0t_64_sync+0x190/0x194
> [    4.013228] SMP: stopping secondary CPUs
>
> The correct way is to wait handshake, but it needs BUS clock of
> BLK-CTL be enabled, which is in separate driver. So delay is the
> only option here. The udelay(10) is a data got by experiment.
>
> Fixes: e8dc41afca16 ("pmdomain: imx: gpcv2: Add delay after power up handshake")
> Reported-by: Francesco Dolcini <francesco@...cini.it>
> Closes: https://lore.kernel.org/lkml/20241007132555.GA53279@francesco-nb/
> Signed-off-by: Shengjiu Wang <shengjiu.wang@....com>

Applied for fixes and by adding a stable tag, thanks!

Kind regards
Uffe

> ---
>  drivers/pmdomain/imx/gpcv2.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/pmdomain/imx/gpcv2.c b/drivers/pmdomain/imx/gpcv2.c
> index 6e6ecbf2e152..760301ad8e39 100644
> --- a/drivers/pmdomain/imx/gpcv2.c
> +++ b/drivers/pmdomain/imx/gpcv2.c
> @@ -403,7 +403,7 @@ static int imx_pgc_power_up(struct generic_pm_domain *genpd)
>                  * already reaches target before udelay()
>                  */
>                 regmap_read_bypassed(domain->regmap, domain->regs->hsk, &reg_val);
> -               udelay(5);
> +               udelay(10);
>         }
>
>         /* Disable reset clocks for all devices in the domain */
> --
> 2.34.1
>