| Message ID | 53EAB01B.5030102@codeaurora.org (mailing list archive) |
|---|---|
| State | Superseded, archived |
| Headers | show |
On 8/12/2014 5:23 PM, Stephen Boyd wrote: > On 08/06/14 17:16, Frank Rowand wrote: >> Stephen, >> >> Can you test this patch on v 1.3 hardware? It works on my v 1.4. >> >> If you use kdmx2, the way to send a break is '~B'. The previous >> key pressed must be <enter> for the '~' escape to be recognized. >> >> Thanks! >> >> -Frank >> >> >> >> From: Frank Rowand <frank.rowand@sonymobile.com> >> >> Add missing sysrq handling to msm_serial. >> >> Signed-off-by: Frank Rowand <frank.rowand@sonymobile.com> >> >> --- > > It works but I have questions. > >> drivers/tty/serial/msm_serial.c | 26 +++++++++++++++++++++----- >> 1 file changed, 21 insertions(+), 5 deletions(-) >> >> Index: b/drivers/tty/serial/msm_serial.c >> =================================================================== >> --- a/drivers/tty/serial/msm_serial.c >> +++ b/drivers/tty/serial/msm_serial.c >> @@ -126,6 +126,8 @@ static void handle_rx_dm(struct uart_por >> >> while (count > 0) { >> unsigned int c; >> + unsigned char *cp; >> + int res; >> >> sr = msm_read(port, UART_SR); >> if ((sr & UART_SR_RX_READY) == 0) { >> @@ -135,15 +137,29 @@ static void handle_rx_dm(struct uart_por >> c = msm_read(port, UARTDM_RF); >> if (sr & UART_SR_RX_BREAK) { >> port->icount.brk++; >> - if (uart_handle_break(port)) >> + if (uart_handle_break(port)) { >> + count -= 1; >> continue; >> + } > > This looks wrong. If it's a break then I think the fifo takes in a break > character indicated by all zeros. We could possibly have 3 other > characters after it in the fifo, or maybe 2 characters in front of it, > or it could be 30 characters in. We can change this behavior by setting > a bit in the MR2 register so that the all zero character doesn't enter > the fifo. The same goes for the parity and frame error conditions, we > can drop those characters too. > > I asked the designers how we're supposed to deal with a break in the > middle of the fifo and they recommended using the start/stop rx break > interrupts. Unfortunately, I don't think we can rely on the interrupts > being distinct so that might not work (but see attached patch). There's > also a break interrupt that triggers on the start and stop rx break > events. I don't know how this is useful either because we might get two > interrupts or we might get one. > > So perhaps we need to scan through the 4 characters for a zero character > when the SR_RX_BREAK bit it set? The second diff does that. > > Add another twist with port->read_status_mask. I guess that's there to > make it so that break characters still enter the tty layer? Is there any > documentation on this stuff? I'm lost on what the tty layer expects. < snip > Yep, the whole break in the middle of a fifo is interesting. If I understand correctly, there is not enough information to determine where in the byte stream the break actually occurred. If interrupts were not disabled for any length of time, then it was probably after all of the characters in the fifo. But I don't like to depend on winning races. As you noted, finding a \0 in the fifo is likely the location in the byte stream where the break occurred. But \0 is also valid data. I read through the two alternate patches that you attached and read some tty layer stuff. Your patches look like better code than my original code, and also leave less cruft in the input stream when stress tested. One stress test that I have not attempted to create is to hold off processing the break until after more character have entered the fifo. The patches you sent are a little hard to read since they modify further code that my patch modified. So I have redone your patches, as if my patch was not previously applied. Hopefully I did not make any mistakes there. I will reply to this email with each of your redone patches. I do not have a strong preference between the two alternatives you provided, without digging deeper into the tty layer, which I won't have time for in the next week. Both alternatives improve the break handling (leave less cruft in the input stream when stress tested than before applying the patches). Both alternatives support sysrq in my testing. If you do not want to submit either of your alternatives, I can dig into this again in a couple weeks. Thanks! -Frank -- To unsubscribe from this list: send the line "unsubscribe linux-arm-msm" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/drivers/tty/serial/msm_serial.c b/drivers/tty/serial/msm_serial.c index e52a4242b7a1..ba66e487c08a 100644 --- a/drivers/tty/serial/msm_serial.c +++ b/drivers/tty/serial/msm_serial.c @@ -125,41 +125,28 @@ static void handle_rx_dm(struct uart_port *port, unsigned int misr) port->icount.rx += count; while (count > 0) { - unsigned int c; - unsigned char *cp; - int res; + unsigned char buf[4]; + unsigned char *p = buf; + int sysrq, r_count; sr = msm_read(port, UART_SR); if ((sr & UART_SR_RX_READY) == 0) { msm_port->old_snap_state -= count; break; } - c = msm_read(port, UARTDM_RF); - if (sr & UART_SR_RX_BREAK) { - port->icount.brk++; - if (uart_handle_break(port)) { - count -= 1; - continue; - } - } else if (sr & UART_SR_PAR_FRAME_ERR) - port->icount.frame++; + readsl(port->membase + UARTDM_RF, p, 1); spin_unlock(&port->lock); - res = uart_handle_sysrq_char(port, c); + sysrq = uart_handle_sysrq_char(port, buf[0]); spin_lock(&port->lock); - - cp = (unsigned char *)&c; - if (res) { - count -= 1; - tty_insert_flip_string(tport, cp + 1, - (count > 3) ? 3 : count); - count -= (count > 3) ? 3 : count; - } else { - tty_insert_flip_string(tport, cp, - (count > 4) ? 4 : count); - count -= (count > 4) ? 4 : count; + if (sysrq) { + p++; + count--; } - + r_count = min_t(int, count, sizeof(buf) - sysrq); + if (r_count) + tty_insert_flip_string(tport, p, r_count); + count -= r_count; } spin_unlock(&port->lock); @@ -301,6 +288,17 @@ static irqreturn_t msm_irq(int irq, void *dev_id) misr = msm_read(port, UART_MISR); msm_write(port, 0, UART_IMR); /* disable interrupt */ + if (misr & UART_IMR_RXBREAK_END) { + uart_handle_break(port); + port->icount.brk++; + msm_write(port, UART_CR_CMD_RESET_RXBREAK_END, UART_CR); + } + + if (misr & UART_IMR_PAR_FRAME_ERR) { + port->icount.frame++; + msm_write(port, UART_CR_CMD_RESET_PAR_FRAME_ERR, UART_CR); + } + if (misr & (UART_IMR_RXLEV | UART_IMR_RXSTALE)) { if (msm_port->is_uartdm) handle_rx_dm(port, misr); @@ -507,7 +505,8 @@ static int msm_startup(struct uart_port *port) /* turn on RX and CTS interrupts */ msm_port->imr = UART_IMR_RXLEV | UART_IMR_RXSTALE | - UART_IMR_CURRENT_CTS; + UART_IMR_CURRENT_CTS | UART_IMR_RXBREAK_END | + UART_IMR_PAR_FRAME_ERR; if (msm_port->is_uartdm) { msm_write(port, 0xFFFFFF, UARTDM_DMRX); @@ -582,6 +581,9 @@ static void msm_set_termios(struct uart_port *port, struct ktermios *termios, else mr |= UART_MR2_STOP_BIT_LEN_ONE; + mr |= UART_MR2_RX_BREAK_ZERO_CHAR_OFF; + mr |= UART_MR2_RX_ERROR_CHAR_OFF; + /* set parity, bits per char, and stop bit */ msm_write(port, mr, UART_MR2); diff --git a/drivers/tty/serial/msm_serial.h b/drivers/tty/serial/msm_serial.h index d98d45efdf86..c2ffa8ba5a34 100644 --- a/drivers/tty/serial/msm_serial.h +++ b/drivers/tty/serial/msm_serial.h @@ -24,6 +24,8 @@ #define UART_MR1_CTS_CTL (1 << 6) #define UART_MR2 0x0004 +#define UART_MR2_RX_ERROR_CHAR_OFF (1 << 9) +#define UART_MR2_RX_BREAK_ZERO_CHAR_OFF (1 << 8) #define UART_MR2_ERROR_MODE (1 << 6) #define UART_MR2_BITS_PER_CHAR 0x30 #define UART_MR2_BITS_PER_CHAR_5 (0x0 << 4) @@ -65,6 +67,9 @@ #define UART_CR_TX_ENABLE (1 << 2) #define UART_CR_RX_DISABLE (1 << 1) #define UART_CR_RX_ENABLE (1 << 0) +#define UART_CR_CMD_RESET_RXBREAK_START ((1 << 11) | (2 << 4)) +#define UART_CR_CMD_RESET_RXBREAK_END ((1 << 11) | (3 << 4)) +#define UART_CR_CMD_RESET_PAR_FRAME_ERR ((1 << 11) | (4 << 4)) #define UART_IMR 0x0014 #define UART_IMR_TXLEV (1 << 0) @@ -72,6 +77,9 @@ #define UART_IMR_RXLEV (1 << 4) #define UART_IMR_DELTA_CTS (1 << 5) #define UART_IMR_CURRENT_CTS (1 << 6) +#define UART_IMR_RXBREAK_START (1 << 10) +#define UART_IMR_RXBREAK_END (1 << 11) +#define UART_IMR_PAR_FRAME_ERR (1 << 12) #define UART_IPR_RXSTALE_LAST 0x20 #define UART_IPR_STALE_LSB 0x1F diff --git a/drivers/tty/serial/msm_serial.c b/drivers/tty/serial/msm_serial.c index e52a4242b7a1..dd68ccdad140 100644 --- a/drivers/tty/serial/msm_serial.c +++ b/drivers/tty/serial/msm_serial.c @@ -125,41 +125,40 @@ static void handle_rx_dm(struct uart_port *port, unsigned int misr) port->icount.rx += count; while (count > 0) { - unsigned int c; - unsigned char *cp; - int res; + unsigned char buf[4]; + int sysrq, r_count, i; sr = msm_read(port, UART_SR); if ((sr & UART_SR_RX_READY) == 0) { msm_port->old_snap_state -= count; break; } - c = msm_read(port, UARTDM_RF); - if (sr & UART_SR_RX_BREAK) { - port->icount.brk++; - if (uart_handle_break(port)) { - count -= 1; - continue; + readsl(port->membase + UARTDM_RF, buf, 1); + + r_count = min_t(int, count, sizeof(buf)); + + for (i = 0; i < r_count; i++) { + char flag = TTY_NORMAL; + + if (sr & UART_SR_RX_BREAK) { + if (buf[i] == 0) { + port->icount.brk++; + flag = TTY_BREAK; + if (uart_handle_break(port)) + continue; + } } - } else if (sr & UART_SR_PAR_FRAME_ERR) - port->icount.frame++; - spin_unlock(&port->lock); - res = uart_handle_sysrq_char(port, c); - spin_lock(&port->lock); + if (!(port->read_status_mask & UART_SR_RX_BREAK)) + flag = TTY_NORMAL; - cp = (unsigned char *)&c; - if (res) { - count -= 1; - tty_insert_flip_string(tport, cp + 1, - (count > 3) ? 3 : count); - count -= (count > 3) ? 3 : count; - } else { - tty_insert_flip_string(tport, cp, - (count > 4) ? 4 : count); - count -= (count > 4) ? 4 : count; + spin_unlock(&port->lock); + sysrq = uart_handle_sysrq_char(port, buf[i]); + spin_lock(&port->lock); + if (!sysrq) + tty_insert_flip_char(tport, buf[i], flag); } - + count -= r_count; } spin_unlock(&port->lock);