Re: [PATCH v3] davinci: Add wl1271/wlan support for AM18x

Ido Yariv
2011-07-28T22:06:49Z

Hi Troy,

On Thu, Jul 28, 2011 at 02:15:41PM -0700, Troy Kisky wrote:
> > + if (power_on) {
> > + /* Power up sequence required for wl127x devices */
> > + gpio_set_value(DA850_WLAN_EN, 1);
> > + usleep_range(15000, 15000);
> > + gpio_set_value(DA850_WLAN_EN, 0);
> > + usleep_range(1000, 1000);
> > + gpio_set_value(DA850_WLAN_EN, 1);
> > + msleep(70);
>
> Why turn on, then off, and then back on?
> Isn't off, then back on sufficient?

Unfortunately, no. This is a required power up sequence for some
hardware revisions of the 1271 chip.

> Also, why not use regulator API like panda board does?

Unlike omap_hsmmc, davinci's MMC host driver does not toggle any
regulators. To keep things simple, a set_power callback function was
added to the mmc host as part of this patch series.
I've considered adding regulator support instead, but found it to be
a bit over-complicated for this task. In addition, it would require
either modifying the fixed regulator or adding a new one in order to
support the above power sequence.

Thanks for your review,
Ido.