linux-kernel - RE: [PATCH 3/3] tty: serial: samsung: Remove unused artpec-8 specific code

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Message-ID: <000101dc2335$ccd62f60$66828e20$@samsung.com>
Date: Thu, 11 Sep 2025 21:34:40 +0530
From: "Ravi Patel" <ravi.patel@...sung.com>
To: "'Krzysztof Kozlowski'" <krzk@...nel.org>, "'Geert Uytterhoeven'"
	<geert@...ux-m68k.org>
Cc: <gregkh@...uxfoundation.org>, <jirislaby@...nel.org>, <robh@...nel.org>,
	<krzk+dt@...nel.org>, <conor+dt@...nel.org>, <jesper.nilsson@...s.com>,
	<lars.persson@...s.com>, <alim.akhtar@...sung.com>, <arnd@...nel.org>,
	<andriy.shevchenko@...ux.intel.com>, <geert+renesas@...der.be>,
	<thierry.bultel.yh@...renesas.com>, <dianders@...omium.org>,
	<robert.marko@...tura.hr>, <schnelle@...ux.ibm.com>, <kkartik@...dia.com>,
	<linux-kernel@...r.kernel.org>, <linux-serial@...r.kernel.org>,
	<devicetree@...r.kernel.org>, <linux-arm-kernel@...ts.infradead.org>,
	<linux-samsung-soc@...r.kernel.org>, <linux-arm-kernel@...s.com>,
	<ksk4725@...sia.com>, <kenkim@...sia.com>, <smn1196@...sia.com>,
	<pjsin865@...sia.com>, <shradha.t@...sung.com>
Subject: RE: [PATCH 3/3] tty: serial: samsung: Remove unused artpec-8
 specific code



> -----Original Message-----
> From: Krzysztof Kozlowski <krzk@...nel.org>
> Sent: 11 September 2025 20:05
...
> Subject: Re: [PATCH 3/3] tty: serial: samsung: Remove unused artpec-8 specific code
> 
> On 11/09/2025 16:29, Krzysztof Kozlowski wrote:
> >>> --- a/drivers/tty/serial/samsung_tty.c
> >>> +++ b/drivers/tty/serial/samsung_tty.c
> >>
> >>> @@ -2655,8 +2621,6 @@ static const struct of_device_id s3c24xx_uart_dt_match[] = {
> >>>                 .data = S5L_SERIAL_DRV_DATA },
> >>>         { .compatible = "samsung,exynos850-uart",
> >>>                 .data = EXYNOS850_SERIAL_DRV_DATA },
> >>> -       { .compatible = "axis,artpec8-uart",
> >>> -               .data = ARTPEC8_SERIAL_DRV_DATA },
> >>>         { .compatible = "google,gs101-uart",
> >>>                 .data = GS101_SERIAL_DRV_DATA },
> >>>         { .compatible = "samsung,exynos8895-uart",
> >>> @@ -2828,8 +2792,6 @@ OF_EARLYCON_DECLARE(s5pv210, "samsung,s5pv210-uart",
> >>>                         s5pv210_early_console_setup);
> >>>  OF_EARLYCON_DECLARE(exynos4210, "samsung,exynos4210-uart",
> >>>                         s5pv210_early_console_setup);
> >>> -OF_EARLYCON_DECLARE(artpec8, "axis,artpec8-uart",
> >>> -                       s5pv210_early_console_setup);
> >>>
> >>>  static int __init gs101_early_console_setup(struct earlycon_device *device,
> >>>                                             const char *opt)
> >>
> >> Removing these breaks backwards-compatibility with existing DTBs,
> >> which lack the new "samsung,exynos8895-uart" fallback compatible value.
> >
> > This was just applied, so ABI break would be fine. It should be however
> > clearly expressed in the commit msg.
> >
> > I have a feeling that not much testing was happening in Samsung around
> > this patchset and only now - after I applied it - some things happen.
> > But it is damn too late, my tree is already closed which means this is
> > going to be the ABI.
> 
> Ah, no, I mixed up patches with recent DTS for Artpec-8. This serial ABI
> was accepted three years ago (!!!), so you are Geert absolutely right -
> that's ABI break.

Thank you for your review.

The DTS patches for ARTPEC-8 is added recently (https://lore.kernel.org/linux-samsung-soc/20250901051926.59970-1-ravi.patel@samsung.com/)
Before that, there was no user (in DT) of "axis,artpec8-uart" compatible.
So I am not convinced of ABI break (considering patch #1 and #2 goes first with review comment fixes)

My intension here is to optimize the driver code (by removing kind of duplicated code)
And also preparation of upcoming ARTPEC-9 patch series where ARTPEC-9 uart is
exactly same as ARTPEC-8.

Please let me know if I misunderstood anything here.

Thanks,
Ravi

> 
> Folks in Samsung, maybe try to organize some weekly sessions sharing
> knowledge after upstreaming reviews/feedbacks? I feel like you are
> repeating same mistakes.
> 
> Best regards,
> Krzysztof