On Thu, Mar 03, 2022 at 03:19:00PM +0000, Ian Dannapel wrote: > Hello I²C Driver Maintainers, Adding the i2c-imx maintainer to CC. > > please excuse me if I am not following the right steps to report a question. I did not find consensus between all instructions that I read. > > We noted that on the IMX i2c driver, at the i2c_imx_start funtion, some sleep/delay was introduced without any apparent reason: > Line 448 at: https://github.com/Freescale/linux-fslc/commit/3a5ee18d2a32bda6b9a1260136f6805848e3839d > Line 528 at: https://github.com/Freescale/linux-fslc/commit/2b899f34e1db9adef8716d07e872a800dfa60790 > Line 200 at: https://github.com/Freescale/linux-fslc/commit/43309f3b521302bb66c4c9e66704dd3675e4d725 > > This sleep causes a pretty big latency overhead on I²C writes and no IMX8MP document states the need of this delay on the controller. NXP Support also informed that this delay might not be needed. > Some early tests with removing this delay completely showed a great reduction on the write latency and no problems with the communication. > > But since we want a stable and fast communication, I ask here again if someone knows the reason or the need for this delay when starting to communicate on the I2C bus. > > I appreciate any response and if further information is needed, I can gladly report it. > > > Best regards, > Ian Dannapel > ian.dannapel@xxxxxxxxxxxxxxxx > • • • • • • • • • • • • • • • • • • • • • • • • • • > iris-GmbH > infrared & intelligent sensors > Schnellerstraße 1-5 | 12439 Berlin > www.iris-sensing.com > > > > >
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