Re: [PATCH 1/8] OMAP: convert I2C driver to PM QoS for latency constraints

[Kevin Hilman <khilman@ti.com>]

Hi Jean,

Jean Pihet <jean.pihet@newoldbits.com> writes:

> Convert the driver from the outdated omap_pm_set_max_mpu_wakeup_lat
> API to the new PM QoS API.
> Since the constraint is on the MPU subsystem, use the PM_QOS_CPU_DMA_LATENCY
> class of PM QoS. The resulting MPU constraints are used by cpuidle to
> decide the next power state of the MPU subsystem.
>
> Currently only OMAP3 is placing constraints on the MPU.
>
> Signed-off-by: Jean Pihet <j-pihet@ti.com>

[...]

> @@ -648,8 +648,16 @@ omap_i2c_xfer(struct i2c_adapter *adap, struct i2c_msg msgs[], int num)
>  	if (r < 0)
>  		goto out;
>  
> -	if (dev->set_mpu_wkup_lat != NULL)
> -		dev->set_mpu_wkup_lat(dev->dev, dev->latency);
> +	/*
> +	 * When waiting for completion of a i2c transfer, we need to
> +	 * set a wake up latency constraint for the MPU. This is to
> +	 * ensure quick enough wakeup from idle, when transfer
> +	 * completes.
> +	 * Used on OMAP3 Only
> +	 */
> +	if (cpu_is_omap34xx())

We don't want any cpu_is_* checking  in drivers.

If this is only done on certain SoCs, then a flag should be passed from
device init code via pdata.

That being said, I don't see why this shouldn't be set for all SoCs
since it's using the FIFO size to determine the latency.

Kevin