[PATCH RFC 0/2] drivers/base: simplify simple DT-based components (original) (raw)

Russell King - ARM Linux linux at arm.linux.org.uk
Fri Feb 7 10:59:11 PST 2014

On Fri, Feb 07, 2014 at 07:42:04PM +0100, Jean-Francois Moine wrote:

On Fri, 7 Feb 2014 17:33:26 +0000 Russell King - ARM Linux <linux at arm.linux.org.uk> wrote:

> On Fri, Feb 07, 2014 at 06:11:08PM +0100, Jean-Francois Moine wrote: > > This patch series tries to simplify the code of simple devices in case > > they are part of componentised subsystems, are declared in a DT, and > > are not using the component bin/unbind functions. > > I wonder - I said earlier today that this works absolutely fine without > modification with DT, so why are you messing about with it adding DT > support? > > This is totally the wrong approach. The idea is that this deals with > /devices/ and /devices/ only. It groups up /devices/. > > It's up to the addcomponent callback to the master device to decide > how to deal with that. > > > Jean-Francois Moine (2): > > drivers/base: permit base components to omit the bind/unbind ops > > And this patch has me wondering if you even understand how to use > this... The master bind/unbind callbacks are the ones which establish > the "card" based context with the subsystem. > > Please, before buggering up this nicely designed implementation, please > /first/ look at the imx-drm rework which was posted back in early January > which illustrates how this is used in a DT context - which is something > I've already pointed you at once today already. As I told in a previous mail, your code works fine in my DT-based Cubox. I am rewriting the TDA988x as a normal encoder/connector, and, yes, the bind/unbind functions are useful in this case.

So, which bit of "I've already got that" was missed?

But you opened a door. In a DT context, you know that the probedefer mechanism does not work correctly. Your work permits to solve delicate cases: your componentadd tells exactly when a device is available, and the master bind callback is the green signal for the device waiting for its resources. Indeed, your system was not created for such a usage, but it works as it is (anyway, the component bind/unbind functions may be empty...).

Sorry. Deferred probe does work, it's been tested with imx-drm, not only from the master component but also the sub-components. There's no problem here.

And no component bind/unbind function should ever be empty.

Again, I put it to you that you don't understand this layer.

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