From mboxrd@z Thu Jan 1 00:00:00 1970 From: Dave Gerlach Subject: Re: [PATCH 1/2] opp: ti-opp-supply: Dynamically update u_volt_min Date: Mon, 12 Nov 2018 16:05:47 -0600 Message-ID: References: <1541565263-8296-1-git-send-email-j-keerthy@ti.com> <1541565263-8296-2-git-send-email-j-keerthy@ti.com> <20181108055401.btrixinlqcfh22du@vireshk-i7> Mime-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: Content-Language: en-US Sender: linux-kernel-owner@vger.kernel.org To: "J, KEERTHY" , Viresh Kumar Cc: vireshk@kernel.org, nm@ti.com, sboyd@kernel.org, linux-pm@vger.kernel.org, linux-kernel@vger.kernel.org, t-kristo@ti.com List-Id: linux-pm@vger.kernel.org On 11/11/2018 09:15 PM, J, KEERTHY wrote: > > > On 11/8/2018 11:24 AM, Viresh Kumar wrote: >> On 07-11-18, 10:04, Keerthy wrote: >>> The voltage range (min, max) provided in the device tree is from >>> the data manual and is pretty big, catering to a wide range of devices. >>> On a i2c read/write failure the regulator_set_voltage_triplet function >>> falls back to set voltage between min and max. The min value from Device >>> Tree can be lesser than the optimal value and in that case that can lead >>> to a hang or crash. Hence set the u_volt_min dynamically to the optimal >>> voltage value. >> >> And why shouldn't we fix the DT for this ? > > The DT voltages do not cater to the broad range of devices. In some > particular cases the DT min voltage is slightly lower the voltage at > which the device cannot sustain a particular frequency in which case the > device just silently hangs. So best thing to do is to actually read the > device specific voltages dynamically which will guarantee a particular > device sustaining a particular frequency at the optimal voltage. > Acked-by: Dave Gerlach >>