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Commit 085a4f75 authored by Feng Tang's avatar Feng Tang Committed by Greg Kroah-Hartman
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serial: mfd: remove the TX full-empty interrupts workaround 



In A0 stepping, TX half-empty interrupt is not working, so have to
use the full-empty interrupts whose performance will be 15% lower.
Now re-enable the half-empty interrrupt after it is enabled in
silicon.

Signed-off-by: default avatarFeng Tang <feng.tang@intel.com>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@suse.de>
parent 10e82f6c

drivers/tty/serial/mfd.c

+5 −21
Original line number Diff line number Diff line
@@ -16,9 +16,7 @@ 
 *    2/3 chan to port 1, 4/5 chan to port 3. Even number chans

 *    are used for RX, odd chans for TX

 *

 * 2. In A0 stepping, UART will not support TX half empty flag

 *

 * 3. The RI/DSR/DCD/DTR are not pinned out, DCD & DSR are always

 * 2. The RI/DSR/DCD/DTR are not pinned out, DCD & DSR are always

 *    asserted, only when the HW is reset the DDCD and DDSR will

 *    be triggered

 */
@@ -41,8 +39,6 @@ 
#include <linux/io.h>

#include <linux/debugfs.h>



#define  MFD_HSU_A0_STEPPING	1



#define HSU_DMA_BUF_SIZE	2048



#define chan_readl(chan, offset)	readl(chan->reg + offset)
@@ -543,16 +539,9 @@ static void transmit_chars(struct uart_hsu_port *up) 
		return;

	}



#ifndef MFD_HSU_A0_STEPPING

	/* The IRQ is for TX FIFO half-empty */

	count = up->port.fifosize / 2;

#else

	/*

	 * A0 only supports fully empty IRQ, and the first char written

	 * into it won't clear the EMPT bit, so we may need be cautious

	 * by useing a shorter buffer

	 */

	count = up->port.fifosize - 4;

#endif



	do {

		serial_out(up, UART_TX, xmit->buf[xmit->tail]);

		xmit->tail = (xmit->tail + 1) & (UART_XMIT_SIZE - 1);
@@ -761,9 +750,8 @@ static void serial_hsu_break_ctl(struct uart_port *port, int break_state) 
/*

 * What special to do:

 * 1. chose the 64B fifo mode

 * 2. make sure not to select half empty mode for A0 stepping

 * 3. start dma or pio depends on configuration

 * 4. we only allocate dma memory when needed

 * 2. start dma or pio depends on configuration

 * 3. we only allocate dma memory when needed

 */

static int serial_hsu_startup(struct uart_port *port)

{
@@ -967,10 +955,6 @@ serial_hsu_set_termios(struct uart_port *port, struct ktermios *termios, 
		fcr = UART_FCR_ENABLE_FIFO | UART_FCR_HSU_64_32B;



	fcr |= UART_FCR_HSU_64B_FIFO;

#ifdef MFD_HSU_A0_STEPPING

	/* A0 doesn't support half empty IRQ */

	fcr |= UART_FCR_FULL_EMPT_TXI;

#endif



	/*

	 * Ok, we're now changing the port state.  Do it with