linux-kernel - RE: [PATCH V3] tty: serial: fsl_lpuart: don't break the on-going transfer when global reset

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Date:   Mon, 24 Oct 2022 08:16:13 +0000
From:   Sherry Sun <sherry.sun@....com>
To:     Jiri Slaby <jirislaby@...nel.org>,
        "gregkh@...uxfoundation.org" <gregkh@...uxfoundation.org>,
        "lukas@...ner.de" <lukas@...ner.de>,
        "ilpo.jarvinen@...ux.intel.com" <ilpo.jarvinen@...ux.intel.com>
CC:     "linux-serial@...r.kernel.org" <linux-serial@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        dl-linux-imx <linux-imx@....com>
Subject: RE: [PATCH V3] tty: serial: fsl_lpuart: don't break the on-going
 transfer when global reset



> -----Original Message-----
> From: Jiri Slaby <jirislaby@...nel.org>
> Sent: 2022年10月24日 14:37
> To: Sherry Sun <sherry.sun@....com>; gregkh@...uxfoundation.org;
> lukas@...ner.de; ilpo.jarvinen@...ux.intel.com
> Cc: linux-serial@...r.kernel.org; linux-kernel@...r.kernel.org; dl-linux-imx
> <linux-imx@....com>
> Subject: Re: [PATCH V3] tty: serial: fsl_lpuart: don't break the on-going
> transfer when global reset
> 
> On 20. 10. 22, 15:19, Sherry Sun wrote:
> > @@ -2636,6 +2610,54 @@ static const struct serial_rs485
> lpuart_rs485_supported = {
> >   	/* delay_rts_* and RX_DURING_TX are not supported */
> >   };
> >
> > +static int lpuart_global_reset(struct lpuart_port *sport) {
> > +	struct uart_port *port = &sport->port;
> > +	void __iomem *global_addr;
> > +	unsigned long ctrl, bd;
> > +	unsigned int val = 0;
> > +	int ret;
> > +
> > +	ret = clk_prepare_enable(sport->ipg_clk);
> > +	if (ret) {
> > +		dev_err(sport->port.dev, "failed to enable uart ipg clk: %d\n",
> ret);
> > +		return ret;
> > +	}
> > +
> > +	if (is_imx7ulp_lpuart(sport) || is_imx8qxp_lpuart(sport)) {
> > +		/*
> > +		 * If the transmitter is used by earlycon, wait for transmit
> engine to
> > +		 * complete and then reset.
> > +		 */
> > +		ctrl = lpuart32_read(port, UARTCTRL);
> > +		if (ctrl & UARTCTRL_TE) {
> > +			bd = lpuart32_read(&sport->port, UARTBAUD);
> > +			if (read_poll_timeout_atomic(lpuart32_tx_empty, val,
> val, 1, 100000,
> > +						     false, port)) {
> 
> Ah, this is not atomic context (clk_prepare_enable() above and
> usleep_range() below), so no need for _atomic here too.
> 

Hi Jiri,
You are right, thanks for the correction, will fix it in V4.

Best Regards
Sherry