[PATCH v4] serial: samsung: change to platform_get_irq_optional

[Krzysztof Kozlowski]

On Mon, Jul 13, 2020 at 07:25:31PM +0530, Tamseel Shams wrote:
> In few older Samsung SoCs like s3c2410, s3c2412
> and s3c2440, UART IP is having 2 interrupt lines.
> However, in other SoCs like s3c6400, s5pv210,
> exynos5433, and exynos4210 UART is having only 1
> interrupt line. Due to this, "platform_get_irq(platdev, 1)"
> call in the driver gives the following false-positive error:
> "IRQ index 1 not found" on recent platforms.
> 
> This patch replaces the platform_get_irq() call with
> platform_get_irq_optional() and hence avoiding the
> false-positive error.

The error is not a false positive on S3C platforms, but a real error.
The existing code did not handle missing TX IRQ but at least printed a
message.  Your change hides the message.

The real problem here is a missing error handling for TX interrupt.
Solving this one, would solve also false-positive error message on newer
SoCs.

Best regards,
Krzysztof