From mboxrd@z Thu Jan 1 00:00:00 1970 From: Rob Herring Date: Thu, 19 Jan 2017 16:22:54 +0000 Subject: Re: [PATCH v2 4/5] fbdev/ssd1307fb: add support to enable VBAT Message-Id: List-Id: References: <214ae9ca86009148f233be71a3606917f3150dcd.1484303628.git.jsarha@ti.com> <20170118223310.kxbgq47v7cl33ls3@rob-hp-laptop> <754f3644-a157-bb90-1494-aba4fc1264f8@ti.com> In-Reply-To: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: Tomi Valkeinen Cc: Jyri Sarha , "linux-fbdev-u79uwXL29TY76Z2rM5mHXA@public.gmane.org" , "devicetree-u79uwXL29TY76Z2rM5mHXA@public.gmane.org" , Bartlomiej Zolnierkiewicz , Maxime Ripard , Benoit Cousson On Thu, Jan 19, 2017 at 9:08 AM, Tomi Valkeinen wrote: > On 19/01/17 17:03, Rob Herring wrote: > >>>> According to the datasheet, SSD1307 has 2 supplies: Vdd and Vcc >>>> >>>> I don't see any mention of a charge pump, so that must be an external >>>> component. >>> >>> VBAT is for SSD1306. Perhaps the DT doc should mention it. >> >> Datasheet says VBAT is reserved, connect to Vdd. I would just describe >> Vdd and Vcc in that case. > > I'm no HW guy, but as far as I understand, you can wire it up two ways. > One has VBAT connected to VDD. The other one has VBAT connected to > external supply. See "Figure 1 : Application Example of SSD1306Z with > charge bump". I should have kept reading... So either Vdd and Vbat supplies or Vdd and Vcc supplies are valid and the former only applies to 1306. Rob