From: Biju Das <biju.das.jz@bp.renesas.com>
To: Chris Brandt <Chris.Brandt@renesas.com>,
Wolfram Sang <wsa+renesas@sang-engineering.com>,
Geert Uytterhoeven <geert+renesas@glider.be>,
Linux-Renesas <linux-renesas-soc@vger.kernel.org>
Cc: Phil Edworthy <phil.edworthy@renesas.com>,
Chris Paterson <Chris.Paterson2@renesas.com>
Subject: RE: Regarding SDHI clocks on RZ/G2L
Date: Tue, 20 Jul 2021 18:43:30 +0000 [thread overview]
Message-ID: <OS0PR01MB5922CEAD71AEAE5256A116C986E29@OS0PR01MB5922.jpnprd01.prod.outlook.com> (raw)
In-Reply-To: <TYCPR01MB6319F7494FB5A69FB00AEA2A8AE29@TYCPR01MB6319.jpnprd01.prod.outlook.com>
Hi Chris,
> Subject: RE: Regarding SDHI clocks on RZ/G2L
>
> Hi Biju,
>
> > -----Original Message-----
> > From: Biju Das
> > Sent: Tuesday, July 20, 2021 11:55 AM
>
> > RZ/G2L document says we should not turn off cd clock during suspend.
> > Otherwise card detection
>
> From a hardware standpoint....yes.
>
> > Won't work. So whether SDHI can reliably work in this case? Basically
> > if there is no activity, this module can go into suspend state. If the
> > cd clock turned off and card detection fails during resume, how the
> > SDHI functionality going to work?
>
> What I am saying is that from a system design standpoint, you need to wake
> up the system first before you can use the SD card (even detecting a card
> insert/remove).
Agreed. That is the usual flow.
>
>
> > Note:-
> > Currently I am configuring CD pin as gpio rather than function due to
> > some reset issue[1]. After reset cd detection fails. But it works ok,
> > if it configured as GPIO.
>
> > 1) Handle it in SDHI driver? ie, enable it during probe only once and
> > > avoid turning it off
> > >
> > > or
> > >
> > > 2) Add this clock as critical clock, so it will be turned on
> > > permanently and don't handle it in SDHI driver?
>
> So does that mean your #1 and #2 both do not work unless the pin is
> configured as GPIO?
With upstream kernel it doesn't work, because of the reset handling patch[1]
4.19 it works, where it doesn't have this patch.
[1] https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/drivers/mmc/host/renesas_sdhi_core.c?h=v5.14-rc2&id=b4d86f37eacb724690d0d300576b82806bc743d5
Regards,
Biju
prev parent reply other threads:[~2021-07-20 18:43 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-07-18 10:25 Regarding SDHI clocks on RZ/G2L Biju Das
2021-07-20 14:47 ` Chris Brandt
2021-07-20 15:54 ` Biju Das
2021-07-20 18:25 ` Chris Brandt
2021-07-20 18:43 ` Biju Das [this message]
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