Re: [PATCH 1/2] opp: ti-opp-supply: Dynamically update u_volt_min

From: J, KEERTHY
Date: Sun Nov 11 2018 - 22:16:00 EST




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.