Messages in this thread |  | | Date | Tue, 19 Sep 2023 17:02:01 +0200 | From | Wolfram Sang <> | Subject | Re: [PATCH 2/2] i2c: rcar: add FastMode+ support for Gen4 |
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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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