On Fri, 4 Aug 2023 15:14:18 +0200
Greg KH [off-list ref] wrote:

On Thu, Aug 03, 2023 at 12:14:49PM -0400, Hugo Villeneuve wrote:

quoted

On Mon, 31 Jul 2023 17:55:42 +0200
Greg KH [off-list ref] wrote:

quoted

On Tue, Jul 25, 2023 at 10:23:36AM -0400, Hugo Villeneuve wrote:

quoted

From: Hugo Villeneuve <hvilleneuve@dimonoff.com>

In preparation for upcoming patch "fix regression with GPIO
configuration". To facilitate review and make code more modular.

I would much rather the issue be fixed _before_ the code is refactored,
unless it is impossible to fix it without the refactor?

Hi Greg,
normally I would agree, but the refactor in this case helps a lot to
address some issues raised by you and Andy in V7 of this series.

Maybe I could merge it with the actual patch "fix regression with GPIO
configuration"?

Sure.

Hi Greg,
will do.

 

quoted

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Cc: <redacted> # 6.1.x

What commit id does this fix?

It doesn't fix anything, but I tought that I needed this tag since
this patch is a prerequisite for the next patch in the series, which
would be applied to stable kernels. I will remove this tag (assuming
the patch stays as it is, depending on your answer to the above
question).

 

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Signed-off-by: Hugo Villeneuve <hvilleneuve@dimonoff.com>
Reviewed-by: Lech Perczak <redacted>
Tested-by: Lech Perczak <redacted>
---
 drivers/tty/serial/sc16is7xx.c | 40 ++++++++++++++++++++--------------
 1 file changed, 24 insertions(+), 16 deletions(-)

diff --git a/drivers/tty/serial/sc16is7xx.c b/drivers/tty/serial/sc16is7xx.c
index 32d43d00a583..5b0aeef9d534 100644
--- a/drivers/tty/serial/sc16is7xx.c
+++ b/drivers/tty/serial/sc16is7xx.c

@@ -332,6 +332,7 @@ struct sc16is7xx_one {
 
 struct sc16is7xx_port {
 	const struct sc16is7xx_devtype	*devtype;
+	struct device			*dev;

Why is this pointer needed?

Why is it grabbed and yet the reference count is never incremented?  Who
owns the reference count and when will it go away?

And what device is this?  The parent?  Current device?  What type of
device is it?  And why is it needed?

Using "raw" devices is almost never something a driver should do, they
are only passed into functions by the driver core, but then the driver
should instantly turn them into the "real" structure.

We already discussed that a lot in previous versions (v7)... I am
trying my best to modify the code to address your concerns, but I am
not fully understanding what you mean about raw devices, and you didn't
answer some of my previous questions/interrogations in v7 about that.

I don't have time to answer all questions, sorry.

Please help review submitted patches to reduce my load and allow me to
answer other stuff :)

Ok.

quoted

So, in the new function that I
need to implement, sc16is7xx_setup_gpio_chip(), I absolutely need to use
a raw device to read a device tree property and to set
s->gpio.parent:

    count = device_property_count_u32(dev, ...
    ...
    s->gpio.parent = dev;

Do we agree on that?

Yes, but what type of parent is that?

I am confused by your question. I do not understand why the type of
parent matters... And what do you call the parent: s, s->gpio or
s->gpio.parent?

For me, the way I understand it, the only question that matters is how I
can extract the raw device structure pointer from maybe "struct
sc16is7xx_port" or some other structure, and then use it in my
new function...

I should not have put "s->gpio.parent = dev" in the example, I think it
just complexifies things. Lets start over with a more simple example and
only:

    count = device_property_count_u32(dev, ...

quoted

Then, how do I pass this raw device to the 
device_property_count_u32() function and to the s->gpio.parent
assignment?

Should I modify sc16is7xx_setup_gpio_chip() like so:

    static int sc16is7xx_setup_gpio_chip(struct sc16is7xx_port *s)
    {
	struct device *dev = &s->p[0].port.dev;

        count = device_property_count_u32(dev, ...
        ...
        s->gpio.parent = dev;

Again, what is the real type of that parent?  It's a port, right, so
pass in the port to this function and then do the "take the struct
device of the port" at that point in time.

With the simplified example, is the following ok:

static int sc16is7xx_setup_gpio_chip(struct sc16is7xx_port *s)
{
    struct device *dev = &s->p[0].port.dev;

    count = device_property_count_u32(dev, ...
    ...
}

If not, please indicate how you would do it with an actual example...

Thank you,
Hugo.