From: Wolfram Sang <wsa+renesas@sang-engineering.com>
To: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: linux-renesas-soc@vger.kernel.org,
Yoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com>,
Andi Shyti <andi.shyti@kernel.org>,
linux-i2c@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH 2/2] i2c: rcar: add FastMode+ support for Gen4
Date: Tue, 19 Sep 2023 17:02:01 +0200 [thread overview]
Message-ID: <ZQm36a4IhPL9kN+g@shikoro> (raw)
In-Reply-To: <CAMuHMdWrb2je4tgEO_OmXhHtFiRb8JfUzBJdUp4KFf574GmoVA@mail.gmail.com>
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> > + /* FM+ needs lower SMD and no filters */
> > + priv->smd /= 2;
> > + cdf = 0;
>
> Is this documented somewhere in the R-Car Gen4 docs?
Sadly, there are no recommended values for FM+ in the docs. With cdf=6,
I got speeds around 800kHz. After seeing the BSP also uses cdf=0, I got
speeds close to 1MHz. There is a note in Gen3 and later docs for ICCCR2
saying that cdf=0 is recommended for devices with a data hold time less
than 100ns. I don't have the PMIC docs here to verify if that is the
case here.
However, I recalled there are some generic filter bindings for I2C. I
will check if we can make use of them here.
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next prev parent reply other threads:[~2023-09-19 15:02 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-09-13 20:32 [PATCH 0/2] i2c: rcar: add support for Gen4 devices Wolfram Sang
2023-09-13 20:32 ` [PATCH 1/2] i2c: rcar: introduce " Wolfram Sang
2023-09-19 9:33 ` Geert Uytterhoeven
2023-09-19 14:24 ` Wolfram Sang
2023-09-13 20:32 ` [PATCH 2/2] i2c: rcar: add FastMode+ support for Gen4 Wolfram Sang
2023-09-19 9:51 ` Geert Uytterhoeven
2023-09-19 15:02 ` Wolfram Sang [this message]
2023-09-14 13:03 ` [PATCH 0/2] i2c: rcar: add support for Gen4 devices Yoshihiro Shimoda
2023-09-16 7:15 ` Wolfram Sang
2023-09-16 11:41 ` Wolfram Sang
2023-09-19 12:23 ` Yoshihiro Shimoda
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