Date:   Wed, 6 Mar 2019 10:11:17 +0000
From:   BOUGH CHEN <haibo.chen@....com>
To:     Aisheng Dong <aisheng.dong@....com>, Stefan Agner <stefan@...er.ch>
CC:     Christina Quast <cquast@...overdisplays.com>,
        "festevam@...il.com" <festevam@...il.com>,
        "shawnguo@...nel.org" <shawnguo@...nel.org>,
        "kernel@...gutronix.de" <kernel@...gutronix.de>,
        "linus.walleij@...aro.org" <linus.walleij@...aro.org>,
        "robh+dt@...nel.org" <robh+dt@...nel.org>,
        "mark.rutland@....com" <mark.rutland@....com>,
        "linux-gpio@...r.kernel.org" <linux-gpio@...r.kernel.org>,
        "devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: RE: [PATCH] Document: dt: binding: imx: Fix PAD_CTL_DSE_X*


> -----Original Message-----
> From: Aisheng Dong
> Sent: 2019年3月5日 11:35
> To: Stefan Agner <stefan@...er.ch>; BOUGH CHEN <haibo.chen@....com>
> Cc: Christina Quast <cquast@...overdisplays.com>; festevam@...il.com;
> shawnguo@...nel.org; kernel@...gutronix.de; linus.walleij@...aro.org;
> robh+dt@...nel.org; mark.rutland@....com; linux-gpio@...r.kernel.org;
> devicetree@...r.kernel.org; linux-kernel@...r.kernel.org; BOUGH CHEN
> <haibo.chen@....com>
> Subject: RE: [PATCH] Document: dt: binding: imx: Fix PAD_CTL_DSE_X*
> 
> + Haibo
> 
> > From: Stefan Agner [mailto:stefan@...er.ch]
> > Sent: Tuesday, February 26, 2019 9:22 PM
> >
> > On 26.02.2019 13:21, Aisheng Dong wrote:
> > >> From: Christina Quast [mailto:cquast@...overdisplays.com]
> > >> Sent: Saturday, February 23, 2019 1:01 AM
> > >>
> > >> In the iMX7d datasheet, the PAD_CTL_DSE_X* values are different
> > >> from the documentation.
> > >>
> > >
> > > It's a doc problem.
> > > Latest RM seems got updated.
> > >
> > > As here it's a reference definition in binding doc and device tree
> > > actually does not use it (IMX Pinctrl use raw data to set pad
> > > configuration). So it won't cause any compatibility issue to me.
> > >
> > > Please update the patch title to:
> > > dt-bindings: pinctrl: imx7d: xxxxx
> > >
> > > Otherwise:
> > > Ack-by: Dong Aisheng <aisheng.dong@....com>
> >
> > Btw, I saw that imx7d-sdb.dts (and probably other i.MX 7 boards too)
> > use three different settings for usdhc pinctrl: 0x59, 0x5a and 0x5b
> > (for default, 100MHz and 200MHz respectively). One would expect that
> > higher frequency use higher driver strength (and this is the case for i.MX 6).
> > But with this new/corrected pad values this means we use x4, x2 and x6
> > for default, 100MHz and 200MHz respectively. This hardly seems right..?
> > Probably needs fixing too?
> >
> 
> Yes, that's true.
> Especially 100Mhz setting should be updated.
> 
> Haibo,
> Can you please help double check if X2 for 50Mhz and X4 for 100Mhz can work
> stably on MX7D SDB?
> If yes, we'd like to update the pad setting according to new RM version.
> 

X2 for high speed and x4 for ddr50/ddr52 can work stable on MX7D SDB.
I think all the 7D related dts need to fix this. Not sure whether 7S need this fix, can you confirm?

Best Regards
Haibo Chen
> Regards
> Dong Aisheng
> 
> > --
> > Stefan
> >
> >
> > >
> > > Regards
> > > Dong Aisheng
> > >
> > >> Signed-off-by: Christina Quast <cquast@...overdisplays.com>
> > >> ---
> > >>  .../devicetree/bindings/pinctrl/fsl,imx7d-pinctrl.txt       | 6 +++---
> > >>  1 file changed, 3 insertions(+), 3 deletions(-)
> > >>
> > >> diff --git
> > >> a/Documentation/devicetree/bindings/pinctrl/fsl,imx7d-pinctrl.txt
> > >> b/Documentation/devicetree/bindings/pinctrl/fsl,imx7d-pinctrl.txt
> > >> index 6666277c3acb..8ac1d0851a0f 100644
> > >> ---
> > >> a/Documentation/devicetree/bindings/pinctrl/fsl,imx7d-pinctrl.txt
> > >> +++ b/Documentation/devicetree/bindings/pinctrl/fsl,imx7d-pinctrl.t
> > >> +++ xt
> > >> @@ -48,9 +48,9 @@ PAD_CTL_HYS                     (1 << 3)
> > >>  PAD_CTL_SRE_SLOW                (1 << 2)
> > >>  PAD_CTL_SRE_FAST                (0 << 2)
> > >>  PAD_CTL_DSE_X1                  (0 << 0)
> > >> -PAD_CTL_DSE_X2                  (1 << 0)
> > >> -PAD_CTL_DSE_X3                  (2 << 0)
> > >> -PAD_CTL_DSE_X4                  (3 << 0)
> > >> +PAD_CTL_DSE_X4                  (1 << 0)
> > >> +PAD_CTL_DSE_X2                  (2 << 0)
> > >> +PAD_CTL_DSE_X6                  (3 << 0)
> > >>
> > >
> > >
> > >>  Examples:
> > >>  While iomuxc-lpsr is intended to be used by dedicated peripherals
> > >> to take
> > >> --
> > >> 2.20.1
> > >>
> > >>
> > >>
> > >>
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