Hello Cedric, On Wed, Jan 11, 2017 at 03:20:41PM +0100, M'boumba Cedric Madianga wrote: > > > >> + */ > >> + reg = i2c_dev->base + STM32F4_I2C_CR1; > >> + stm32f4_i2c_clr_bits(reg, STM32F4_I2C_CR1_ACK); > >> + stm32f4_i2c_set_bits(reg, STM32F4_I2C_CR1_POS); > > > > You could get rid of this, when caching the value of CR1. Would save two > > register reads here. This doesn't work for all registers, but it should > > be possible to apply for most of them, maybe enough to get rid of the > > clr_bits and set_bits function. > > I agree at many places I could save registers read by not using > clr_bits and set_bits function when the registers in question has been > already read. > But it is not enough to get rid of the clr_bits and set_bits function. > For example when calling stm32f4_i2c_terminate_xfer(), the CR1 > register is never read before so set_bits function is useful. I didn't double check the manual, but I would expect that CR1 isn't modified by hardware. So you can cache the result in the driver data structure and do the necessary modifications with that one. Best regards Uwe -- Pengutronix e.K. | Uwe Kleine-König | Industrial Linux Solutions | http://www.pengutronix.de/ | -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
