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Subject: Re: [PATCH v14 13/19] leds: lp55xx: Add multicolor framework support
 to lp55xx
To:     Jacek Anaszewski <jacek.anaszewski@gmail.com>, <pavel@ucw.cz>
CC:     <linux-leds@vger.kernel.org>, <linux-kernel@vger.kernel.org>
References: <20191018122521.6757-1-dmurphy@ti.com>
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 <0cd2082a-16d7-c414-7bd2-708a97885da1@gmail.com>
 <b469d35b-ca39-2a99-1e86-420edcabf1ac@ti.com>
 <bfcae4c2-aa4d-8460-528f-6029d7a87b4d@gmail.com>
 <74868064-6a40-172e-ce28-94722e1f1aaf@ti.com>
 <7814c28c-ed38-24f0-6ff2-d89c918b617e@gmail.com>
From:   Dan Murphy <dmurphy@ti.com>
Message-ID: <4273a125-129b-1c8b-b5ba-d320da40bf2a@ti.com>
Date:   Fri, 25 Oct 2019 15:07:06 -0500
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Jacek

On 10/25/19 1:56 PM, Jacek Anaszewski wrote:
> Dan,
>
> On 10/25/19 8:18 PM, Dan Murphy wrote:
>> Jacek
>>
>> On 10/25/19 1:13 PM, Jacek Anaszewski wrote:
>>> Dan,
>>>
>>> On 10/25/19 7:57 PM, Dan Murphy wrote:
>>>> Jacek
>>>>
>>>> On 10/22/19 12:41 PM, Jacek Anaszewski wrote:
>>>>> Dan,
>>>>>
>>>>> On 10/22/19 6:37 PM, Dan Murphy wrote:
>>>>>> Jacek
>>>>>>
>>>>>> On 10/18/19 4:56 PM, Jacek Anaszewski wrote:
>>>>>>> On 10/18/19 11:48 PM, Jacek Anaszewski wrote:
>>>>>>>> Dan,
>>>>>>> +        ret = lp5xx_parse_channel_child(child, cfg, i);
>>>>>>>> I went into details of this parsing and finally came up with
>>>>>>>> the code which is a bit greater in size, but IMHO cleaner.
>>>>>>>> Note changes in variable naming. It is not even compile-tested.
>>>>>>>>
>>>>>>>> static int lp55xx_parse_common_child(struct device_node *np,
>>>>>>>>                                         struct lp55xx_led_config
>>>>>>>> *cfg,
>>>>>>>>                                         int led_number, int *chan_nr)
>>>>>>>> {
>>>>>>>>             int ret;
>>>>>>>>
>>>>>>>>             of_property_read_string(np, "chan-name",
>>>>>>>>                                     &cfg[led_number].name);
>>>>>>>>             of_property_read_u8(np, "led-cur",
>>>>>>>>                                 &cfg[led_number].led_current);
>>>>>>>>             of_property_read_u8(np, "max-cur",
>>>>>>>>                                 &cfg[led_number].max_current);
>>>>>>>>
>>>>>>>>             ret = of_property_read_u32(np, "reg", chan_nr);
>>>>>>>>             if (ret)
>>>>>>>>                     return ret;
>>>>>>>>
>>>>>>>>             if (chan_nr < 0 || chan_nr > cfg->max_chan_nr) /* side
>>>>>>>> note:
>>>>>>>> new
>>>>>>>> max_chan_nr property needed in cfg */
>>>>>>>>                     return -EINVAL;
>>>>>>>>
>>>>>>>>             return 0;
>>>>>>>> }
>>>>>>>>
>>>>>>>> static int lp55xx_parse_mutli_led_child(struct device_node *np,
>>>>>>>>                                             struct lp55xx_led_config
>>>>>>>> *cfg,
>>>>>>>>                                             int child_number,
>>>>>>>>                                             int color_number)
>>>>>>>> {
>>>>>>>>             int chan_nr, color_id;
>>>>>>>>
>>>>>>>>             ret = lp55xx_parse_common_child(child, cfg, child_number,
>>>>>>>> color_number,
>>>>>>>>                                             &chan_nr);
>>>>>>>>             if (ret)
>>>>>>>>                     return ret;
>>>>>>>>
>>>>>>>>             ret = of_property_read_u32(child, "color", &color_id);
>>>>>>>>             if (ret)
>>>>>>>>                    return ret;
>>>>>>>>
>>>>>>>>            
>>>>>>>> cfg[child_number].color_components[color_number].color_id =
>>>>>>>> color_id;
>>>>>>>>           
>>>>>>>> cfg[child_number].color_components[color_number].output_num =
>>>>>>>> chan_nr;
>>>>>>>>             set_bit(color_id, &cfg[child_number].available_colors);
>>>>>>>>
>>>>>>>>             return 0;
>>>>>>>> }
>>>>>>>>
>>>>>>>> staitc int lp55xx_parse_mutli_led(struct device_node *np,
>>>>>>>>                                       struct lp55xx_led_config *cfg,
>>>>>>>>                                       int child_number)
>>>>>>>> {
>>>>>>>>             struct device_node *child;
>>>>>>>>             int num_colors = 0, i = 0;
>>>>>>> s/, i = 0//
>>>>>>>
>>>>>>>>             for_each_child_of_node(np, child) {
>>>>>>>>                     ret = lp55xx_parse_mutli_led_child(child, cfg,
>>>>>>>> num_colors,
>>>>>>>>                                                       
>>>>>>>> child_number, i))
>>>>>>> Replace above call with below:
>>>>>>>
>>>>>>> ret = lp55xx_parse_mutli_led_child(child, cfg, child_number,
>>>>>>> num_colors);
>>>>>>>
>>>>>> I applied your DT parser patch from the v13 series.  Which eliminates
>>>>>> this comment correct?
>>>>> Yes, it contains this fix.
>>>>>
>>>> OK I added your patch and it broke a lot of the DT parsing for the
>>>> LP55xx.
>>>>
>>>> I would prefer to stick with the original code without having to
>>>> re-write this again.
>>> Let me test that with Qemu first.
>>>
>> max_channel is never set so not sure where that is supposed to come from
>> since each child device has different number of channels.  And if the
>> user has to populate that information from the DT then it does not make
>> sense as the user would already be aware of the number of channels.
>> This information would have to come from the child device some how and
>> the children do not have access to the structure to set it.
> This was my silent assumption that the child will initialize that.
> And I was not thoroughly seeking the most proper place for this
> property, just chose first I could think . You are free to
> change its location so that it was accessible for the child.
>
OK  I got it limping along now by passing in the chip->cfg to the 
populate data along with rearranging the child probe.

I think it is a lot of change to check 1 value but I can include it

>> In checking the chan_nr to the max_channels you are comparing a pointer
>> to an integer.  Easy fix but did not solve the registration issues.
>>
>> cfg->num_colors is not set anywhere so the registration always goes to
>> base led_registration.  Unless we key off a different value to determine
>> to register to multicolor class or not.  Or we default this to the
>> multi_class registration to figure out how to register based on
>> available_colors.
> You need to add below at the end of lp55xx_parse_mutli_led():
>
> cfg[child_number].num_colors = num_colors;
>
> and below in led_parse_logical_led() at the end of the
> "if (ret)" branch.
>
> cfg[child_number].num_colors = 1;

This was added

>> That is what I am seeing so far in my debugging and I still don't have
>> it working.
> I didn't pretend it was flawless, just wanted to show general idea
> how I would see that.
>
Yes I know you only compile tested this.

Dan