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Message-ID: <e8cf9ed3-e2d3-4764-b1c3-87e38e99b4a5@gmx.de>
Date:   Thu, 14 Dec 2023 10:00:00 +0100
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Subject: Re: [PATCH V5 3/3] tty: serial: uartps: Add rs485 support to uartps
 driver
Content-Language: en-US
To:     Manikanta Guntupalli <manikanta.guntupalli@amd.com>, git@amd.com,
        michal.simek@amd.com, gregkh@linuxfoundation.org,
        robh+dt@kernel.org, krzysztof.kozlowski+dt@linaro.org,
        conor+dt@kernel.org, linux-serial@vger.kernel.org,
        devicetree@vger.kernel.org, linux-kernel@vger.kernel.org,
        jirislaby@kernel.org, linux-arm-kernel@lists.infradead.org
Cc:     radhey.shyam.pandey@amd.com, srinivas.goud@amd.com,
        shubhrajyoti.datta@amd.com, manion05gk@gmail.com
References: <20231213130023.606486-1-manikanta.guntupalli@amd.com>
 <20231213130023.606486-4-manikanta.guntupalli@amd.com>
From:   Lino Sanfilippo <LinoSanfilippo@gmx.de>
In-Reply-To: <20231213130023.606486-4-manikanta.guntupalli@amd.com>
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Precedence: bulk


Hi,

On 13.12.23 14:00, Manikanta Guntupalli wrote:

>
> +/**
> + * cdns_rs485_rx_callback - Timer rx callback handler for rs485.
> + * @t: Handle to the timer list structure
> + */
> +static void cdns_rs485_rx_callback(struct timer_list *t)
> +{
> +	struct cdns_uart *cdns_uart =3D from_timer(cdns_uart, t, timer);
> +
> +	/*
> +	 * Default Rx should be setup, because Rx signaling path
> +	 * need to enable to receive data.
> +	 */
> +	cdns_rs485_rx_setup(cdns_uart);
> +}
> +
> +/**
> + * cdns_rs485_tx_callback - Timer tx callback handler for rs485.
> + * @t: Handle to the timer list structure
> + */
> +static void cdns_rs485_tx_callback(struct timer_list *t)
> +{
> +	struct cdns_uart *cdns_uart =3D from_timer(cdns_uart, t, timer);
> +
> +	cdns_uart_handle_tx(cdns_uart->port);

This is called without holding the port lock now. Are you sure the lock is=
 not
needed? AFAIK the port lock is needed at least for accessing the circular
buffer.

> +
> +	/* Enable the TX Empty interrupt */
> +	writel(CDNS_UART_IXR_TXEMPTY, cdns_uart->port->membase + CDNS_UART_IER=
);
> +
> +	if (uart_circ_empty(&cdns_uart->port->state->xmit) ||
> +	    uart_tx_stopped(cdns_uart->port)) {
> +		timer_setup(&cdns_uart->timer, cdns_rs485_rx_callback, 0);
> +		mod_timer(&cdns_uart->timer, jiffies +
> +			  msecs_to_jiffies(cdns_uart->port->rs485.delay_rts_after_send));
> +	}
> +}

Regards,
Lino