From: Lee Jones <lee@kernel.org>
To: Samuel Holland <samuel@sholland.org>
Cc: Pavel Machek <pavel@ucw.cz>,
linux-leds@vger.kernel.org, Chen-Yu Tsai <wens@csie.org>,
Jernej Skrabec <jernej.skrabec@gmail.com>,
linux-kernel@vger.kernel.org, linux-sunxi@lists.linux.dev
Subject: Re: [RESEND PATCH v7 2/5] leds: sun50i-a100: New driver for the A100 LED controller
Date: Tue, 31 Oct 2023 07:48:07 +0000 [thread overview]
Message-ID: <20231031074807.GQ8909@google.com> (raw)
In-Reply-To: <f5468eac-96ec-e8c9-bcc1-9ec219bf3352@sholland.org>
On Sun, 29 Oct 2023, Samuel Holland wrote:
> Hi Lee,
>
> On 10/17/23 19:38, Samuel Holland wrote:
> > On 3/16/23 08:34, Lee Jones wrote:
> >> On Sat, 31 Dec 2022, Samuel Holland wrote:
> >>> + for_each_available_child_of_node(np, child) {
> >>> + struct sun50i_a100_ledc_led *led;
> >>> + struct led_classdev *cdev;
> >>> + u32 addr, color;
> >>> +
> >>> + ret = of_property_read_u32(child, "reg", &addr);
> >>> + if (ret || addr >= count) {
> >>> + dev_err(dev, "LED 'reg' values must be from 0 to %d\n",
> >>
> >> Doesn't sounds like an address.
> >
> > The one-wire protocol involves the first LED responding to the first 24
> > bits of the transfer, then forwarding the rest to the next LED. The
> > address is the ordinal position in the chain. So I don't think there is
> > any reason to have gaps in the addresses--the LEDs would still have to
> > physically be there, but you would not be able to control them. That
> > said, the driver doesn't need to enforce this, so I can remove the check.
>
> There's actually a reason for the driver enforcing that LED addresses
> are contiguous. Removing this check decouples the largest address from
> the number of LED class devices. Unfortunately, there's a register field
> (LEDC_RESET_TIMING_CTRL_REG_LED_NUM) that must be set to the largest
> address for transfers to work correctly.
>
> This means the driver would need to iterate through the child nodes in
> two passes inside the probe function: first to find the largest reg
> value, and second to actually register the LED class devices.
>
> Since I don't think having gaps in the addresses is a realistic use
> case, I'd like to keep this restriction for now (with a comment). We
> could always pay the complexity cost later if someone really does want
> to relax this check.
You're replying to a review conducted 7 months ago which in turn was for
a patch submitted nearly a year ago!
Also the review comment was simple - if it's not an address, rename the
variable.
--
Lee Jones [李琼斯]
next prev parent reply other threads:[~2023-10-31 7:48 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-12-31 23:55 [RESEND PATCH v7 0/5] leds: Allwinner A100 LED controller support Samuel Holland
2022-12-31 23:55 ` [RESEND PATCH v7 1/5] dt-bindings: leds: Add Allwinner A100 LED controller Samuel Holland
2022-12-31 23:55 ` [RESEND PATCH v7 2/5] leds: sun50i-a100: New driver for the " Samuel Holland
2023-01-09 17:16 ` Lee Jones
2023-03-01 14:27 ` Lee Jones
2023-03-16 13:34 ` Lee Jones
2023-10-18 0:38 ` Samuel Holland
2023-10-29 18:37 ` Samuel Holland
2023-10-31 7:48 ` Lee Jones [this message]
2023-10-19 20:26 ` André Apitzsch
2023-10-23 9:58 ` Lee Jones
2023-11-17 12:54 ` Lee Jones
2022-12-31 23:55 ` [RESEND PATCH v7 3/5] arm64: dts: allwinner: a100: Add LED controller node Samuel Holland
2022-12-31 23:55 ` [RESEND PATCH v7 4/5] riscv: dts: allwinner: d1: " Samuel Holland
2022-12-31 23:55 ` [RESEND PATCH v7 5/5] riscv: dts: allwinner: d1: Add RGB LEDs to boards Samuel Holland
2023-01-26 4:59 ` [RESEND PATCH v7 0/5] leds: Allwinner A100 LED controller support Trevor Woerner
2023-03-07 20:56 ` Palmer Dabbelt
2023-03-08 4:13 ` Guo Ren
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