On Wed, Oct 12, 2016 at 12:30:29PM +0200, Heiko Stuebner wrote:

Hi,

Am Dienstag, 20. September 2016, 11:36:41 CEST schrieb Peter Chen:

quoted

We have an well-known problem that the device needs to do some power
sequence before it can be recognized by related host, the typical
example like hard-wired mmc devices and usb devices.

This power sequence is hard to be described at device tree and handled by
related host driver, so we have created a common power sequence
library to cover this requirement. The core code has supplied
some common helpers for host driver, and individual power sequence
libraries handle kinds of power sequence for devices.

pwrseq_generic is intended for general purpose of power sequence, which
handles gpios and clocks currently, and can cover regulator and pinctrl
in future. The host driver just needs to call of_pwrseq_on/of_pwrseq_off
if only one power sequence is needed, else call of_pwrseq_on_list
/of_pwrseq_off_list instead (eg, USB hub driver).

Signed-off-by: Peter Chen <redacted>
Tested-by Joshua Clayton [off-list ref]
Reviewed-by: Matthias Kaehlcke <mka@chromium.org>
Tested-by: Matthias Kaehlcke <mka@chromium.org>

first of all, glad to see this move forward. I've only some qualms with the 
static number of allocated power sequences below.

Thanks for commenting it, the preallocate way is not a good way, but I
can't find suitable way. See below comments.

quoted

+static int __init pwrseq_generic_register(void)
+{
+	struct pwrseq_generic *pwrseq_gen;
+	int i;
+
+	for (i = 0; i < CONFIG_PWRSEQ_GENERIC_INSTANCE_NUMBER; i++) {
+		pwrseq_gen = kzalloc(sizeof(*pwrseq_gen), GFP_KERNEL);
+		if (!pwrseq_gen)
+			return -ENOMEM;
+
+		pwrseq_gen->pwrseq.pwrseq_of_match_table = generic_id_table;
+		pwrseq_gen->pwrseq.get = pwrseq_generic_get;
+		pwrseq_gen->pwrseq.on = pwrseq_generic_on;
+		pwrseq_gen->pwrseq.off = pwrseq_generic_off;
+		pwrseq_gen->pwrseq.put = pwrseq_generic_put;
+		pwrseq_gen->pwrseq.free = pwrseq_generic_free;
+
+		pwrseq_register(&pwrseq_gen->pwrseq);
+	}
+
+	return 0;
+}
+postcore_initcall(pwrseq_generic_register)

I see that you need to have it preallocated for the compatible matching, but 
wouldn't it also work to either just register the type and allocate 
dynamically or otherwise just allocate a new spare everytime 
pwrseq_generic_get() picks up the previous spare?

Before compatible matching, the host driver doesn't know which pwrseq type
for its child node, then doesn't know which pwrseq instance needs to be
allocated. From dts, we don't know which pwrseq type for the node.

-- 

Best Regards,
Peter Chen