linux-kernel - Re: [PATCH 16/16] soc: imx: gpcv2: remove waiting handshake in power up

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Date:   Fri, 30 Apr 2021 10:47:08 +0200
From:   Lucas Stach <l.stach@...gutronix.de>
To:     "Peng Fan (OSS)" <peng.fan@....nxp.com>, robh+dt@...nel.org,
        shawnguo@...nel.org, s.hauer@...gutronix.de
Cc:     kernel@...gutronix.de, festevam@...il.com, linux-imx@....com,
        p.zabel@...gutronix.de, krzk@...nel.org, agx@...xcpu.org,
        marex@...x.de, andrew.smirnov@...il.com,
        devicetree@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        linux-kernel@...r.kernel.org, ping.bai@....com,
        frieder.schrempf@...tron.de, aford173@...il.com, abel.vesa@....com,
        Peng Fan <peng.fan@....com>
Subject: Re: [PATCH 16/16] soc: imx: gpcv2: remove waiting handshake in
 power up

Am Freitag, dem 30.04.2021 um 15:14 +0800 schrieb Peng Fan (OSS):
> 
> On 2021/4/29 22:34, Lucas Stach wrote:
> > Am Donnerstag, dem 29.04.2021 um 15:30 +0800 schrieb Peng Fan (OSS):
> > > From: Peng Fan <peng.fan@....com>
> > > 
> > > i.MX8MM has blk ctl module, the handshake can only finish after setting
> > > blk ctl. The blk ctl driver will set the bus clk bit and the handshake
> > > will finish there. we just add a delay and suppose the handshake will
> > > finish after that.
> > 
> > Instead of this patch, just drop patch 05/16 from this series. I think
> > we should leave a comment in the code on why we aren't waiting for the
> > handshake ack, as this is non-obvious from looking at the driver code.
> > 
> > Basically add a polished version of the commit log from this patch into
> > the driver code.
> 
> After thinking more, for power down, we need wait handshake. For power 
> up, we could ignore handshake, because BLK-CTL setting bus clk en
> will auto trigger handshake.
> 
> For power down, the bus clk en already set, and we need wait, otherwise
> we need add delay there.
> 
> So I would only drop the power up waiting and add some comments there.

Ah, right. This way makes a lot of sense.

Regards,
Lucas