linux-kernel - Re: [PATCH v2 22/25] tty: serial: samsung

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Date:   Thu, 18 Feb 2021 23:16:40 +0900
From:   Hector Martin <marcan@...can.st>
To:     Krzysztof Kozlowski <krzk@...nel.org>
Cc:     linux-arm-kernel@...ts.infradead.org,
        Marc Zyngier <maz@...nel.org>, Rob Herring <robh@...nel.org>,
        Arnd Bergmann <arnd@...nel.org>,
        Olof Johansson <olof@...om.net>,
        Mark Kettenis <mark.kettenis@...all.nl>,
        Tony Lindgren <tony@...mide.com>,
        Mohamed Mediouni <mohamed.mediouni@...amail.com>,
        Stan Skowronek <stan@...ellium.com>,
        Alexander Graf <graf@...zon.com>,
        Will Deacon <will@...nel.org>,
        Linus Walleij <linus.walleij@...aro.org>,
        Mark Rutland <mark.rutland@....com>,
        devicetree@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 22/25] tty: serial: samsung_tty: Add support for Apple
 UARTs

On 16/02/2021 04.13, Krzysztof Kozlowski wrote:
> On Mon, Feb 15, 2021 at 09:17:10PM +0900, Hector Martin wrote:
>> @@ -389,10 +396,12 @@ static void enable_tx_pio(struct s3c24xx_uart_port *ourport)
>>   	ucon = rd_regl(port, S3C2410_UCON);
>>   	ucon &= ~(S3C64XX_UCON_TXMODE_MASK);
>>   	ucon |= S3C64XX_UCON_TXMODE_CPU;
>> -	wr_regl(port,  S3C2410_UCON, ucon);
>>   
>>   	/* Unmask Tx interrupt */
>>   	switch (ourport->info->type) {
>> +	case TYPE_APPLE_S5L:
>> +		ucon |= APPLE_S5L_UCON_TXTHRESH_ENA_MSK;
>> +		break;
>>   	case TYPE_S3C6400:
>>   		s3c24xx_clear_bit(port, S3C64XX_UINTM_TXD, S3C64XX_UINTM);
>>   		break;
>> @@ -401,7 +410,16 @@ static void enable_tx_pio(struct s3c24xx_uart_port *ourport)
>>   		break;
>>   	}
>>   
>> +	wr_regl(port,  S3C2410_UCON, ucon);
> 
> You are now configuring the PIO mode after unmasking interrupt. I don't
> think it's a good idea to change the order... and if it were, it
> would deserve a separate patch.

For v3 I moved the wr_regl back and just write it again in the 
TYPE_APPLE_S5L branch; that way, setting the PIO mode and unmasking the 
interrupt are two discrete operations on S5L, like they are on other types.

>>   	/* Keep all interrupts masked and cleared */
>>   	switch (ourport->info->type) {
>> +	case TYPE_APPLE_S5L: {
> 
> Usually you put TYPE_APPLE at the end of switch, so please keep it
> consistent. Can be first or last - just everywhere the same, unless you
> have a fall-through on purpose.

Good point, thanks, moved it for v3. It was actually inconsistent in 
more places, I made all the orders the same (the enum order, and 
default: always goes at the end).

>> @@ -2179,6 +2329,32 @@ static int s3c24xx_serial_resume_noirq(struct device *dev)
>>   	if (port) {
>>   		/* restore IRQ mask */
>>   		switch (ourport->info->type) {
>> +		case TYPE_APPLE_S5L: {
>> +			unsigned int ucon;
>> +
>> +			clk_prepare_enable(ourport->clk);
>> +			if (!IS_ERR(ourport->baudclk))
>> +				clk_prepare_enable(ourport->baudclk);
> 
> We should start checking the return values of clk operations. I know
> that existing code does it only in few places, so basically you are not
> making it worse...

Added error checking for these for v3, thanks.

>> +#define S5L_SERIAL_DRV_DATA ((kernel_ulong_t)&s5l_serial_drv_data)
>> +#else
>> +#define S5L_SERIAL_DRV_DATA ((kernel_ulong_t)NULL)
>> +#endif
>> +
>> +
> 
> Only one line break.

Fixed in v3.

Thank you for the reviews!

-- 
Hector Martin (marcan@...can.st)
Public Key: https://mrcn.st/pub