Hello Mark, On 2/8/22 16:18, Mark Brown wrote: > On Tue, Feb 08, 2022 at 04:10:49PM +0100, Javier Martinez Canillas wrote: >> On 2/8/22 15:19, Geert Uytterhoeven wrote: > >>> - "time ls" on the serial console (no files in the current directory, >>> so nothing to print) increases from 0.86s to 1.92s, so the system is >>> more loaded. As ssd1307fb relied on deferred I/O too, the slowdown >>> might be (partly) due to redrawing of the visual artefacts >>> mentioned above. > >> I was trying to first have the driver and then figure out how to optimize >> it. For v3 I'm using regmap to access instead of the I2C layer directly. > >> I noticed that this is even slower but it makes the driver more clean and >> allows to support both I2C and SPI (untested but will include it as a WIP). > > I wouldn't have expected regmap to add huge overhead relative to I2C, > partly predicated on I2C being rather slow itself. There will be some > overhead for concurrency protection and data marshalling but for I2C > clocked at normal speeds it's surprising. Thanks for chiming in. That's good to know, I'll investigate more then. Probably I was wrongly blaming regmap while it was another change that is causing the display to be refreshed at a slower rate than before. Best regards, -- Javier Martinez Canillas Linux Engineering Red Hat
