[PATCH] i2c: omap: improve duty cycle on SCL
balbi at ti.com
Tue Jun 16 12:19:48 PDT 2015
On Tue, Jun 16, 2015 at 02:17:56PM -0500, Felipe Balbi wrote:
> With this patch we try to be as close to 50%
> duty cycle as possible. The reason for this
> is that some devices present an erratic behavior
> with certain duty cycles.
> One such example is TPS65218 PMIC which fails
> to change voltages when running @ 400kHz and
> duty cycle is lower than 34%.
> The idea of the patch is simple:
> calculate desired scl_period from requested scl
> and use 50% for tLow and 50% for tHigh.
> tLow is calculated with a DIV_ROUND_UP() to make
> sure it's slightly higher than tHigh and to make
> sure that we end up within I2C specifications.
> Kudos to Nishanth Menon and Dave Gerlach for helping
> debugging the TPS65218 problem found on AM437x SK.
> Signed-off-by: Felipe Balbi <balbi at ti.com>
the patch is correct, but I sent the version written on top of v3.14,
I'll resend correct version, sorry.
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