On Sun, 8 Aug 2021 at 14:37, Martin Blumenstingl
[off-list ref] wrote:

Hi Mathieu,

On Thu, Aug 5, 2021 at 6:15 PM Mathieu Poirier
[off-list ref] wrote:

quoted

On Wed, Aug 04, 2021 at 11:03:57PM +0200, Martin Blumenstingl wrote:

quoted

Hi Mathieu,

thanks for taking the time to look into this!

(I will address any of your comments that I am not mentioning in this
email anymore. Thanks a lot for the suggestions!)

On Wed, Jul 28, 2021 at 7:58 PM Mathieu Poirier
[off-list ref] wrote:
[...]

quoted

quoted

+     writel(FIELD_PREP(AO_REMAP_REG0_REMAP_AHB_SRAM_BITS_17_14_FOR_ARM_CPU,
+                            priv->sram_pa >> 14),

Indentation problem

The idea here is to align priv->sram_pa with AO_REMAP_REG0... which
are both arguments to FIELD_PREP

Right, this is what I would have expected.  When I applied the patch on my side
"priv->sram_pa ..." was aligned wiht the 'M' of "AO_REMAP_ ...".

quoted

Maybe using something like this will make that easier to read:
    tmp = FIELD_PREP(AO_REMAP_REG0_REMAP_AHB_SRAM_BITS_17_14_FOR_ARM_CPU,
                                     priv->sram_pa >> 14);
    writel(tmp, priv->remap_base + AO_REMAP_REG0);

I think the main problem is that
AO_REMAP_REG0_REMAP_AHB_SRAM_BITS_17_14_FOR_ARM_CPU is simply too long.  I
suggest making is shorter and add a comment to describe exactly what it does.

AO_CPU_CNTL_AHB_SRAM_BITS_31_20 is used below and when looking at it
now I think the alignment is also strange.
For the next version I'll go with the tmp variable as I think it
improves readability, even with the long(er) macro names.

[...]

quoted

quoted

quoted

quoted

+     priv->arc_reset = devm_reset_control_get_exclusive(dev, NULL);
+     if (IS_ERR(priv->arc_reset)) {

Function __reset_control_get() in __devm_reset_control_get() can return NULL so
this should be IS_ERR_OR_NULL().

The logic in there is: return optional ? NULL : ERR_PTR(-...);

Ok, so you meant to do that.  And I just checked reset_control_reset() and it does
account for a NULL parameter.  I'm good with this one but add a comment to
make sure future readers don't think you've omitted to properly deal with the
NULL return value.

quoted

I am requesting a mandatory reset line here, so reset core will never
return NULL
See also [0]

Indeed, I've read that too.  Nonetheless __reset_control_get() can return NULL
by way of __reset_control_get_from_lookup().

I could not find where __reset_control_get_from_lookup returns NULL in
case optional is false (which it is in this case because
devm_reset_control_get_exclusive requests a "mandatory" reset line).
Can you please point me to the problematic line(s) as I'd like to send
a patch (which fixes this) to the reset subsystem maintainers

I am currently traveling - I will get back to you in a week or so.

$ git grep -A1 devm_reset_control_get_exclusive | grep IS_ERR_OR_NULL
drivers/remoteproc/ti_k3_r5_remoteproc.c-       if
(IS_ERR_OR_NULL(core->reset)) {
$

I suspect that this can be simplified then as well.


Best regards,
Martin


[0] https://elixir.bootlin.com/linux/v5.14-rc4/source/include/linux/reset.h#L227
[1] https://elixir.bootlin.com/linux/v5.14-rc4/source/drivers/reset/core.c#L932

_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel