[PATCH 7/8] serial: imx: use readl() to optimize FIFO reading loop

[Sergey Organov]

Ilpo Järvinen <ilpo.jarvinen at linux.intel.com> writes:

> On Fri, 13 Jan 2023, Sergey Organov wrote:
>
>> Use readl() instead of heavier imx_uart_readl() in the Rx ISR, as we know
>> we read registers that must not be cached.
>> 
>> Signed-off-by: Sergey Organov <sorganov at gmail.com>
>> ---
>>  drivers/tty/serial/imx.c | 5 +++--
>>  1 file changed, 3 insertions(+), 2 deletions(-)
>> 
>> diff --git a/drivers/tty/serial/imx.c b/drivers/tty/serial/imx.c
>> index be00362b8b67..f4236e8995fa 100644
>> --- a/drivers/tty/serial/imx.c
>> +++ b/drivers/tty/serial/imx.c
>> @@ -890,14 +890,15 @@ static irqreturn_t __imx_uart_rxint(int irq, void *dev_id)
>>  	struct imx_port *sport = dev_id;
>>  	unsigned int rx, flg;
>>  	struct tty_port *port = &sport->port.state->port;
>> +	typeof(sport->port.membase) membase = sport->port.membase;
>>  	u32 usr2;
>>  
>>  	/* If we received something, check for 0xff flood */
>> -	usr2 = imx_uart_readl(sport, USR2);
>> +	usr2 = readl(membase + USR2);
>>  	if (usr2 & USR2_RDR)
>>  		imx_uart_check_flood(sport, usr2);
>>  
>> -	while ((rx = imx_uart_readl(sport, URXD0)) & URXD_CHARRDY) {
>> +	while ((rx = readl(membase + URXD0)) & URXD_CHARRDY) {
>>  		flg = TTY_NORMAL;
>>  		sport->port.icount.rx++;
>
> I'd just make a uport local variable and use uport->membase + xx. There 
> are plenty of sport->port constructs to replace with uport in that 
> function anyway.

OK, thanks, will do it this way. Probably with global rename over this
function in a separate patch?

-- 
Sergey