Re: [PATCH] i2c: omap: improve duty cycle on SCL

[Felipe Balbi <balbi@ti.com>]

[-- Attachment #1: Type: text/plain, Size: 957 bytes --]

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@ti.com>

the patch is correct, but I sent the version written on top of v3.14,
I'll resend correct version, sorry.

-- 
balbi

[-- Attachment #2: Digital signature --]
[-- Type: application/pgp-signature, Size: 819 bytes --]