From: Krzysztof Kozlowski <krzysztof.kozlowski@canonical.com>
To: Hector Martin <marcan@marcan.st>,
Andy Shevchenko <andy.shevchenko@gmail.com>
Cc: linux-arm Mailing List <linux-arm-kernel@lists.infradead.org>,
Marc Zyngier <maz@kernel.org>, Rob Herring <robh@kernel.org>,
Arnd Bergmann <arnd@kernel.org>, Olof Johansson <olof@lixom.net>,
Mark Kettenis <mark.kettenis@xs4all.nl>,
Tony Lindgren <tony@atomide.com>,
Mohamed Mediouni <mohamed.mediouni@caramail.com>,
Stan Skowronek <stan@corellium.com>,
Alexander Graf <graf@amazon.com>, Will Deacon <will@kernel.org>,
Linus Walleij <linus.walleij@linaro.org>,
Mark Rutland <mark.rutland@arm.com>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
Jonathan Corbet <corbet@lwn.net>,
Catalin Marinas <catalin.marinas@arm.com>,
Christoph Hellwig <hch@infradead.org>,
"David S. Miller" <davem@davemloft.net>,
devicetree <devicetree@vger.kernel.org>,
"open list:SERIAL DRIVERS" <linux-serial@vger.kernel.org>,
Linux Documentation List <linux-doc@vger.kernel.org>,
Linux Samsung SOC <linux-samsung-soc@vger.kernel.org>,
Linux-Arch <linux-arch@vger.kernel.org>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
Subject: Re: [RFT PATCH v3 24/27] tty: serial: samsung_tty: Add support for Apple UARTs
Date: Sun, 7 Mar 2021 12:40:02 +0100 [thread overview]
Message-ID: <b742457e-bf74-0e93-1d24-26f29a0b873a@canonical.com> (raw)
In-Reply-To: <2ed7523f-5c11-976f-ac11-f756d7510400@marcan.st>
On 05/03/2021 18:04, Hector Martin wrote:
> On 06/03/2021 00.28, Andy Shevchenko wrote:
>>> + case TYPE_APPLE_S5L:
>>> + WARN_ON(1); // No DMA
>>
>> Oh, no, please use the ONCE variant.
>
> Thanks, changing this for v4.
>
>>
>> ...
>>
>>> + /* Apple types use these bits for IRQ masks */
>>> + if (ourport->info->type != TYPE_APPLE_S5L) {
>>> + ucon &= ~(S3C64XX_UCON_TIMEOUT_MASK |
>>> + S3C64XX_UCON_EMPTYINT_EN |
>>> + S3C64XX_UCON_DMASUS_EN |
>>> + S3C64XX_UCON_TIMEOUT_EN);
>>> + ucon |= 0xf << S3C64XX_UCON_TIMEOUT_SHIFT |
>>
>> Can you spell 0xf with named constant(s), please?
>>
>> In case they are repetitive via the code, introduce either a temporary
>> variable (in case it scoped to one function only), or define it as a
>> constant.
>
> I'm just moving this code; as far as I can tell this is a timeout value
> (so just an integer), but I don't know if there is any special meaning
> to 0xf here. Note that this codepath is for *non-Apple* chips, as the
> Apple ones don't even have this field (at least not here).
I agree here with Hector. Andi, you propose here unrelated change (which
without documentation might not be doable by Hector).
>
>>> + irqreturn_t ret = IRQ_NONE;
>>
>> Redundant. You may return directly.
>
> What if both interrupts are pending?
>
>> No IO serialization?
>
> There is no DMA on the Apple variants (as far as I know; it's not
> implemented anyway), so there is no need for serializing IO with DMA. In
> any case, dealing with that is the DMA code's job, the interrupt handler
> shouldn't need to care.
>
> If you mean serializing IO with the IRQ: CPU-wise, I would hope that's
> the irqchip's job (AIC does this with a readl on the event). If you mean
> ensuring all writes are complete (i.e. posted write issue), on the Apple
> chips everything is non-posted as explained in the previous patches.
>
>> Extra blank line (check your entire series for a such)
>
> Thanks, noted. I'll check the declaration blocks in other patches.
>
>>> + ourport->rx_enabled = 1;
>>> + ourport->tx_enabled = 0;
>>
>> How are these protected against race?
>
> The serial core should be holding the port mutex for pretty much every
> call into the driver, as far as I can tell.
>
>>
>> ...
>>
>>> + case TYPE_APPLE_S5L: {
>>> + unsigned int ucon;
>>> + int ret;
>>> +
>>> + ret = clk_prepare_enable(ourport->clk);
>>> + if (ret) {
>>> + dev_err(dev, "clk_enable clk failed: %d\n", ret);
>>> + return ret;
>>> + }
>>> + if (!IS_ERR(ourport->baudclk)) {
>>> + ret = clk_prepare_enable(ourport->baudclk);
>>> + if (ret) {
>>> + dev_err(dev, "clk_enable baudclk failed: %d\n", ret);
>>> + clk_disable_unprepare(ourport->clk);
>>> + return ret;
>>> + }
>>> + }
>>
>> Wouldn't it be better to use CLK bulk API?
>
> Ah, I guess that could save a line or two of code here, even though it
> requires setting up the array. I'll give it a shot.
>
>>> +#ifdef CONFIG_ARCH_APPLE
>>
>> Why? Wouldn't you like the one kernel to work on many SoCs?
>
> This *adds* Apple support, it is not mutually exclusive with all the
> other SoCs. You can enable all of those options and get a driver that
> works on all of them. This is the same pattern used throughout the
> driver for all the other Samsung variants. There is no reason to have
> Apple SoC support in the samsung driver if the rest of the kernel
> doesn't have Apple SoC support either, of course.
How ifdef on ARCH_APLLE makes it non-working on many SoCs? All new
platforms are multi... The true question is - do the ifdefs in the code
make it more difficult to read/review?
Best regards,
Krzysztof
next prev parent reply other threads:[~2021-03-07 11:41 UTC|newest]
Thread overview: 136+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-03-04 21:38 [RFT PATCH v3 00/27] Apple M1 SoC platform bring-up Hector Martin
2021-03-04 21:38 ` [RFT PATCH v3 01/27] arm64: Cope with CPUs stuck in VHE mode Hector Martin
2021-03-24 18:05 ` Will Deacon
2021-03-24 20:00 ` Marc Zyngier
2021-03-26 7:54 ` Hector Martin
2021-03-04 21:38 ` [RFT PATCH v3 02/27] dt-bindings: vendor-prefixes: Add apple prefix Hector Martin
2021-03-08 20:26 ` Rob Herring
2021-03-04 21:38 ` [RFT PATCH v3 03/27] dt-bindings: arm: apple: Add bindings for Apple ARM platforms Hector Martin
2021-03-05 10:16 ` Linus Walleij
2021-03-08 20:27 ` Rob Herring
2021-03-04 21:38 ` [RFT PATCH v3 04/27] dt-bindings: arm: cpus: Add apple,firestorm & icestorm compatibles Hector Martin
2021-03-08 20:27 ` Rob Herring
2021-03-04 21:38 ` [RFT PATCH v3 05/27] arm64: cputype: Add CPU implementor & types for the Apple M1 cores Hector Martin
2021-03-24 18:13 ` Will Deacon
2021-03-04 21:38 ` [RFT PATCH v3 06/27] dt-bindings: timer: arm,arch_timer: Add interrupt-names support Hector Martin
2021-03-05 10:18 ` Linus Walleij
2021-03-08 11:12 ` Marc Zyngier
2021-03-08 17:14 ` Tony Lindgren
2021-03-08 20:38 ` Rob Herring
2021-03-08 22:42 ` Marc Zyngier
2021-03-09 16:11 ` Rob Herring
2021-03-09 20:28 ` Hector Martin
2021-03-04 21:38 ` [RFT PATCH v3 07/27] arm64: arch_timer: implement support for interrupt-names Hector Martin
2021-03-05 10:19 ` Linus Walleij
2021-03-08 11:13 ` Marc Zyngier
2021-03-04 21:38 ` [RFT PATCH v3 08/27] asm-generic/io.h: Add a non-posted variant of ioremap() Hector Martin
2021-03-05 14:45 ` Andy Shevchenko
2021-03-05 15:19 ` Hector Martin
2021-03-08 11:20 ` Marc Zyngier
2021-03-24 18:12 ` Will Deacon
2021-03-24 19:09 ` Arnd Bergmann
2021-03-25 14:07 ` Hector Martin
2021-03-25 14:49 ` Will Deacon
2021-03-04 21:38 ` [RFT PATCH v3 09/27] docs: driver-api: device-io: Document I/O access functions Hector Martin
2021-03-05 10:22 ` Linus Walleij
2021-03-04 21:38 ` [RFT PATCH v3 10/27] docs: driver-api: device-io: Document ioremap() variants & access funcs Hector Martin
2021-03-05 10:25 ` Linus Walleij
2021-03-05 15:09 ` Andy Shevchenko
2021-03-05 15:51 ` Arnd Bergmann
2021-03-09 20:29 ` Hector Martin
2021-03-04 21:38 ` [RFT PATCH v3 11/27] arm64: Implement ioremap_np() to map MMIO as nGnRnE Hector Martin
2021-03-08 11:22 ` Marc Zyngier
2021-03-24 18:18 ` Will Deacon
2021-03-04 21:38 ` [RFT PATCH v3 12/27] of/address: Add infrastructure to declare MMIO as non-posted Hector Martin
2021-03-05 10:28 ` Linus Walleij
2021-03-05 15:13 ` Andy Shevchenko
2021-03-05 15:55 ` Hector Martin
2021-03-05 16:08 ` Andy Shevchenko
2021-03-05 16:43 ` Arnd Bergmann
2021-03-05 17:19 ` Hector Martin
2021-03-05 16:05 ` Rob Herring
2021-03-05 17:39 ` Rob Herring
2021-03-05 18:18 ` Hector Martin
2021-03-05 21:17 ` Arnd Bergmann
2021-03-08 15:56 ` Rob Herring
2021-03-08 20:29 ` Arnd Bergmann
2021-03-08 21:13 ` Rob Herring
2021-03-08 21:56 ` Arnd Bergmann
2021-03-09 15:48 ` Rob Herring
2021-03-09 20:23 ` Hector Martin
2021-03-09 22:06 ` Rob Herring
2021-03-10 8:26 ` Hector Martin
2021-03-10 17:01 ` Rob Herring
2021-03-11 9:12 ` Arnd Bergmann
2021-03-11 12:11 ` Hector Martin
2021-03-11 13:35 ` Arnd Bergmann
2021-03-11 16:07 ` Rob Herring
2021-03-11 16:48 ` Arnd Bergmann
2021-03-11 18:10 ` Rob Herring
2021-03-12 10:20 ` Arnd Bergmann
2021-03-09 11:14 ` Linus Walleij
2021-03-09 12:41 ` Arnd Bergmann
2021-03-09 15:40 ` Linus Walleij
2021-03-04 21:38 ` [RFT PATCH v3 13/27] arm64: Add Apple vendor-specific system registers Hector Martin
2021-03-24 18:38 ` Will Deacon
2021-03-24 18:59 ` Mark Rutland
2021-03-24 19:04 ` Will Deacon
2021-03-26 6:23 ` Hector Martin
2021-03-04 21:38 ` [RFT PATCH v3 14/27] arm64: move ICH_ sysreg bits from arm-gic-v3.h to sysreg.h Hector Martin
2021-03-08 11:39 ` Marc Zyngier
2021-03-24 18:23 ` Will Deacon
2021-03-04 21:38 ` [RFT PATCH v3 15/27] dt-bindings: interrupt-controller: Add DT bindings for apple-aic Hector Martin
2021-03-08 21:16 ` Rob Herring
2021-03-04 21:38 ` [RFT PATCH v3 16/27] irqchip/apple-aic: Add support for the Apple Interrupt Controller Hector Martin
2021-03-05 15:05 ` Andy Shevchenko
2021-03-08 11:50 ` Marc Zyngier
2021-03-08 12:02 ` Andy Shevchenko
2021-03-26 13:40 ` Hector Martin
2021-03-08 13:31 ` Marc Zyngier
2021-03-26 7:57 ` Hector Martin
2021-03-24 19:57 ` Will Deacon
2021-03-26 8:58 ` Hector Martin
2021-03-29 12:04 ` Will Deacon
2021-04-01 13:16 ` Hector Martin
2021-03-04 21:38 ` [RFT PATCH v3 17/27] arm64: Kconfig: Introduce CONFIG_ARCH_APPLE Hector Martin
2021-03-08 15:35 ` Marc Zyngier
2021-03-09 20:30 ` Hector Martin
2021-03-04 21:38 ` [RFT PATCH v3 18/27] tty: serial: samsung_tty: Separate S3C64XX ops structure Hector Martin
2021-03-05 10:30 ` Krzysztof Kozlowski
2021-03-04 21:38 ` [RFT PATCH v3 19/27] tty: serial: samsung_tty: Add ucon_mask parameter Hector Martin
2021-03-05 10:34 ` Krzysztof Kozlowski
2021-03-04 21:38 ` [RFT PATCH v3 20/27] tty: serial: samsung_tty: Add s3c24xx_port_type Hector Martin
2021-03-05 10:49 ` Krzysztof Kozlowski
2021-03-04 21:38 ` [RFT PATCH v3 21/27] tty: serial: samsung_tty: IRQ rework Hector Martin
2021-03-05 10:51 ` Krzysztof Kozlowski
2021-03-05 15:17 ` Andy Shevchenko
2021-03-05 16:16 ` Hector Martin
2021-03-05 16:20 ` Andy Shevchenko
2021-03-05 16:29 ` Hector Martin
2021-03-07 11:34 ` Krzysztof Kozlowski
2021-03-07 16:01 ` Arnd Bergmann
2021-03-07 19:51 ` Krzysztof Kozlowski
2021-03-04 21:38 ` [RFT PATCH v3 22/27] tty: serial: samsung_tty: Use devm_ioremap_resource Hector Martin
2021-03-05 10:54 ` Krzysztof Kozlowski
2021-03-05 15:19 ` Andy Shevchenko
2021-03-04 21:38 ` [RFT PATCH v3 23/27] dt-bindings: serial: samsung: Add apple,s5l-uart compatible Hector Martin
2021-03-08 21:17 ` Rob Herring
2021-03-04 21:38 ` [RFT PATCH v3 24/27] tty: serial: samsung_tty: Add support for Apple UARTs Hector Martin
2021-03-05 10:58 ` Krzysztof Kozlowski
2021-03-05 15:28 ` Andy Shevchenko
2021-03-05 17:04 ` Hector Martin
2021-03-07 11:40 ` Krzysztof Kozlowski [this message]
2021-03-04 21:39 ` [RFT PATCH v3 25/27] tty: serial: samsung_tty: Add earlycon " Hector Martin
2021-03-05 10:55 ` Krzysztof Kozlowski
2021-03-10 23:11 ` Linus Walleij
2021-03-04 21:39 ` [RFT PATCH v3 26/27] dt-bindings: display: Add apple,simple-framebuffer Hector Martin
2021-03-08 21:18 ` Rob Herring
2021-03-09 16:37 ` Linus Walleij
2021-03-09 20:35 ` Hector Martin
2021-03-04 21:39 ` [RFT PATCH v3 27/27] arm64: apple: Add initial Apple Mac mini (M1, 2020) devicetree Hector Martin
2021-03-05 11:03 ` Krzysztof Kozlowski
2021-03-05 11:14 ` Hector Martin
2021-03-05 11:45 ` Krzysztof Kozlowski
2021-03-05 15:59 ` Mark Kettenis
2021-03-05 16:50 ` Hector Martin
2021-03-05 10:11 ` [RFT PATCH v3 00/27] Apple M1 SoC platform bring-up Hector Martin
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