[PATCH] Powerpc 8xx CPM_UART setting MAXIDL register proportionaly to baud rate
From: Christophe Leroy <hidden>
Date: 2012-09-24 06:41:14
MAXIDL is the timeout after which a receive buffer is closed when not full if no more characters are received. We calculate it from the baudrate so that the duration is always the same at standard rates: about 4ms. At 9600 bauds it gives a timeout of 4 characters, which is the timeout on the 8250 UART. Signed-off-by: Christophe Leroy <redacted>
--- linux-3.5-vanilla/drivers/tty/serial/cpm_uart/cpm_uart_core.c 2012-07-21 22:58:29.000000000 +0200
+++ linux-3.5/drivers/tty/serial/cpm_uart/cpm_uart_core.c 2012-08-09 17:38:37.000000000 +0200@@ -501,6 +501,7 @@ struct uart_cpm_port *pinfo = (struct uart_cpm_port *)port; smc_t __iomem *smcp = pinfo->smcp; scc_t __iomem *sccp = pinfo->sccp; + int maxidl; pr_debug("CPM uart[%d]:set_termios\n", port->line);
@@ -511,6 +512,17 @@ else pinfo->rx_fifosize = RX_BUF_SIZE; + /* MAXIDL is the timeout after which a receive buffer is closed + * when not full if no more characters are received. + * We calculate it from the baudrate so that the duration is + * always the same at standard rates: about 4ms. + */ + maxidl = baud / 2400; + if (maxidl < 1) + maxidl = 1; + if (maxidl > 0x10) + maxidl = 0x10; + /* Character length programmed into the mode register is the * sum of: 1 start bit, number of data bits, 0 or 1 parity bit, * 1 or 2 stop bits, minus 1.
@@ -611,6 +623,7 @@ * SMC/SCC receiver is disabled. */ out_be16(&pinfo->smcup->smc_mrblr, pinfo->rx_fifosize); + out_be16(&pinfo->smcup->smc_maxidl, maxidl); /* Set the mode register. We want to keep a copy of the * enables, because we want to put them back if they were
@@ -623,6 +636,7 @@ SMCMR_SM_UART | prev_mode); } else { out_be16(&pinfo->sccup->scc_genscc.scc_mrblr, pinfo->rx_fifosize); + out_be16(&pinfo->sccup->scc_maxidl, maxidl); out_be16(&sccp->scc_psmr, (sbits << 12) | scval); }