Re: [PATCH 1/8] usb: typec: fusb302: Make fusb302_set_cc_polarity also set pull ups / downs

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On Tue, Apr 16, 2019 at 04:44:39PM +0300, Heikki Krogerus wrote:
> On Tue, Apr 16, 2019 at 12:19:53PM +0200, Greg Kroah-Hartman wrote:
> > On Fri, Feb 22, 2019 at 03:11:58PM +0100, Hans de Goede wrote:
> > > The 2 callers of fusb302_set_cc_polarity both call fusb302_set_cc_pull
> > > directly before calling fusb302_set_cc_polarity, this is not ideal for
> > > 2 reasons:
> > > 
> > > 1) fusb302_set_cc_pull uses the cached polarity when applying pull-ups,
> > > which maybe changed immediately afterwards, to fix this set_cc_polarity
> > > already does the pull-up setting.
> > > 
> > > 2) Both touch the SWITCHES0 register in a r-w-modify cycle, this leads to
> > > read reg, write reg, read reg, write reg. If we fold the setting of
> > > the pull-downs into fusb302_set_cc_polarity then not only can we avoid
> > > doing the reads / writes twice, at this point we set all bits, so we
> > > can skip the read, turning 4 (slowish) i2c-transfers into 1.
> > > 
> > > Doing this also avoids the need to cache the pull_up state in
> > > struct fusb302_chip.
> > > 
> > > Signed-off-by: Hans de Goede <hdegoede@xxxxxxxxxx>
> > > ---
> > >  drivers/usb/typec/tcpm/fusb302.c | 48 +++++++++++---------------------
> > >  1 file changed, 16 insertions(+), 32 deletions(-)
> > 
> > It would be nice to get some people to review/ack this series before I
> > take it (hint...)
> 
> Hans send second and third version of these. These are already in.

Ah, nevermind then, now dropped :)

greg k-h



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