From mboxrd@z Thu Jan 1 00:00:00 1970 From: Mark Brown Subject: Re: [PATCH v4 2/4] mmc: core: Add mmc_regulator_set_vqmmc() Date: Fri, 20 Mar 2015 11:28:28 +0000 Message-ID: <20150320112828.GF2869@sirena.org.uk> References: <1426112117-18220-1-git-send-email-dianders@chromium.org> <1426112117-18220-2-git-send-email-dianders@chromium.org> <20150319113646.GQ2869@sirena.org.uk> Mime-Version: 1.0 Content-Type: multipart/mixed; boundary="===============7828116290016607737==" Return-path: In-Reply-To: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "Linux-rockchip" Errors-To: linux-rockchip-bounces+glpar-linux-rockchip=m.gmane.org-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org To: Ulf Hansson Cc: Addy Ke , Andrew Gabbasov , Alexandru Stan , "open list:ARM/Rockchip SoC..." , Seungwon Jeon , "linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org" , Sascha Hauer , linux-mmc , Doug Anderson , Chris Ball , Jaehoon Chung , Andrew Bresticker , Tim Kryger , Alim Akhtar , Johan Rudholm , Adrian Hunter , Sonny Rao , Javier Martinez Canillas , "linux-arm-kernel-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org" , Heiko Stuebner List-Id: linux-rockchip.vger.kernel.org --===============7828116290016607737== Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="4fo3mGi7Q6pk/+I3" Content-Disposition: inline --4fo3mGi7Q6pk/+I3 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline On Fri, Mar 20, 2015 at 11:55:50AM +0100, Ulf Hansson wrote: > On 19 March 2015 at 12:36, Mark Brown wrote: > > The implementation *should* do that anyway, it's just not trivial to > > implement in an efficient fashion with the current information we have > > from drivers. > The APIs regulator_count_voltages() and regulator_list_voltage(), are > currently used from the mmc core to find out which voltages that is > supported (with 0.1V granularity). Then that information can be used > when trying to set a new voltage. > But I guess such a wrapper API is out of the question? > Anyway, I get the feeling that we will need to do the same for this case. As previously discussed the problem is that there can be a *lot* of voltages on a modern regulator with fine grained voltage steps and tolerances are also used for things like cpufreq where we care about performance. We need something that doesn't require a linear scan of possible values. > >> would be good to allow both upper and lower limits to be zero. > > The lower limit can be zero already though it isn't clear to me that > > this is useful. Setting an upper limit of zero seems nonsensical, an > > upper limit that is lower than the lower limit isn't terribly obvious > > and removing the upper limit isn't safe - it means that we'll happily > > oversupply things which is a road to physical damage. > I am not sure I follow here. In the regulator_set_voltage_tol() you > can only specifiy one limit (tolerance?). What Dough proposed was to > add a new API which can have both a low tolerance value and a high > tolerance value. Tolerances are not limits - when you say "limit" that sounds like a hard value. I can't see any reason why the code would prevent anyone setting a tolerance of zero, though it should be rare that this is actually the best thing to do. --4fo3mGi7Q6pk/+I3 Content-Type: application/pgp-signature; name="signature.asc" Content-Description: Digital signature -----BEGIN PGP SIGNATURE----- Version: GnuPG v2 iQEcBAEBCAAGBQJVDARbAAoJECTWi3JdVIfQiPQH+wVECwfALfzRrxDM2hMMzyoO EdpJfak+mGZrowaxAyb4AcfS1qxEETng0G2bK67QM2cX38ZvWnPZTRd3fG/huIZ4 VIlW63RyR5KGOUYa4QNplp4XdYt41d3fuc1Zee3iqEkCDfngoacWgdoYYh61h7F0 acEcg7nN1IjCLMp5c+aRAKsKKwpfJyYaQn3tSyS31sBKtk35tqZyGNO5Fl4k+vAg ZJnAzzIpeEPJ+xiqt6WTb+Qr9R6+QIp/sxsfzbuYzbT5noAYBvj1Vknc4x+q/51E 93eHG+dcRrfqfx+FrfKtId9ObsYRfBQhHz+gogkQPSix75SPGUcKioc5eDj9hKY= =pyen -----END PGP SIGNATURE----- --4fo3mGi7Q6pk/+I3-- --===============7828116290016607737== Content-Type: text/plain; charset="us-ascii" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit Content-Disposition: inline _______________________________________________ Linux-rockchip mailing list Linux-rockchip-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org http://lists.infradead.org/mailman/listinfo/linux-rockchip --===============7828116290016607737==--