2023-08-22 12:31:28

by Tony Lindgren

[permalink] [raw]
Subject: Re: [PATCH] bus: ti-sysc: Use fsleep() instead of usleep_range() in sysc_reset()

* Julien Panis <[email protected]> [230821 14:24]:
> The am335x-evm started producing boot errors because of subtle timing
> changes:
>
> Unhandled fault: external abort on non-linefetch (0x1008) at 0xf03c1010
> ...
> sysc_reset from sysc_probe+0xf60/0x1514
> sysc_probe from platform_probe+0x5c/0xbc
> ...
>
> The fix consists in using the appropriate sleep function in sysc reset.
> For flexible sleeping, fsleep is recommended. Here, sysc delay parameter
> can take any value in [0 - 255] us range. As a result, fsleep() should
> be used, calling udelay() for a sysc delay lower than 10 us.
>
> Signed-off-by: Julien Panis <[email protected]>
> Fixes: e709ed70d122 ("bus: ti-sysc: Fix missing reset delay handling")
> ---
> Fix boot errors for am335x-evm in sysc_reset(), by using fsleep() instead
> of usleep_range() function. Thus, udelay() will be called if the configured
> sysc delay is lower than 10 us (which is usually the case, since the value
> set in the device tree is currently 2 us).

OK, interesting. Yeah I've only ever seen values of 2 us needed here.

Regards,

Tony

> ---
> drivers/bus/ti-sysc.c | 3 +--
> 1 file changed, 1 insertion(+), 2 deletions(-)
>
> diff --git a/drivers/bus/ti-sysc.c b/drivers/bus/ti-sysc.c
> index 4cb23b9e06ea..59b8bdd9203e 100644
> --- a/drivers/bus/ti-sysc.c
> +++ b/drivers/bus/ti-sysc.c
> @@ -2147,8 +2147,7 @@ static int sysc_reset(struct sysc *ddata)
> }
>
> if (ddata->cfg.srst_udelay)
> - usleep_range(ddata->cfg.srst_udelay,
> - ddata->cfg.srst_udelay * 2);
> + fsleep(ddata->cfg.srst_udelay);
>
> if (ddata->post_reset_quirk)
> ddata->post_reset_quirk(ddata);
>
> ---
> base-commit: f7757129e3dea336c407551c98f50057c22bb266
> change-id: 20230821-fix-ti-sysc-reset-5c164051345b
>
> Best regards,
> --
> Julien Panis <[email protected]>
>


2023-09-13 08:29:54

by Tony Lindgren

[permalink] [raw]
Subject: Re: [PATCH] bus: ti-sysc: Use fsleep() instead of usleep_range() in sysc_reset()

* Tony Lindgren <[email protected]> [230822 09:27]:
> * Julien Panis <[email protected]> [230821 14:24]:
> > The am335x-evm started producing boot errors because of subtle timing
> > changes:
> >
> > Unhandled fault: external abort on non-linefetch (0x1008) at 0xf03c1010
> > ...
> > sysc_reset from sysc_probe+0xf60/0x1514
> > sysc_probe from platform_probe+0x5c/0xbc
> > ...
> >
> > The fix consists in using the appropriate sleep function in sysc reset.
> > For flexible sleeping, fsleep is recommended. Here, sysc delay parameter
> > can take any value in [0 - 255] us range. As a result, fsleep() should
> > be used, calling udelay() for a sysc delay lower than 10 us.
> >
> > Signed-off-by: Julien Panis <[email protected]>
> > Fixes: e709ed70d122 ("bus: ti-sysc: Fix missing reset delay handling")
> > ---
> > Fix boot errors for am335x-evm in sysc_reset(), by using fsleep() instead
> > of usleep_range() function. Thus, udelay() will be called if the configured
> > sysc delay is lower than 10 us (which is usually the case, since the value
> > set in the device tree is currently 2 us).
>
> OK, interesting. Yeah I've only ever seen values of 2 us needed here.

Applied into fixes thanks

Tony