From: Ronald Wahl ronald.wahl@raritan.com
Starting RX DMA on THRI interrupt is too early because TX may not have finished yet.
This change is inspired by commit 90b8596ac460 ("serial: 8250: Prevent starting up DMA Rx on THRI interrupt") and fixes DMA issues I had with an AM62 SoC that is using the 8250 OMAP variant.
Cc: stable@vger.kernel.org Fixes: c26389f998a8 ("serial: 8250: 8250_omap: Add DMA support for UARTs on K3 SoCs") Signed-off-by: Ronald Wahl ronald.wahl@raritan.com --- V3: - add Cc: stable@vger.kernel.org
V2: - add Fixes: tag - fix author
drivers/tty/serial/8250/8250_omap.c | 9 +++++---- 1 file changed, 5 insertions(+), 4 deletions(-)
diff --git a/drivers/tty/serial/8250/8250_omap.c b/drivers/tty/serial/8250/8250_omap.c index c7ab2963040b..f2f59ec6b50b 100644 --- a/drivers/tty/serial/8250/8250_omap.c +++ b/drivers/tty/serial/8250/8250_omap.c @@ -1282,10 +1282,11 @@ static int omap_8250_dma_handle_irq(struct uart_port *port)
status = serial_port_in(port, UART_LSR);
- if (priv->habit & UART_HAS_EFR2) - am654_8250_handle_rx_dma(up, iir, status); - else - status = omap_8250_handle_rx_dma(up, iir, status); + if ((iir & 0x3f) != UART_IIR_THRI) + if (priv->habit & UART_HAS_EFR2) + am654_8250_handle_rx_dma(up, iir, status); + else + status = omap_8250_handle_rx_dma(up, iir, status);
serial8250_modem_status(up); if (status & UART_LSR_THRE && up->dma->tx_err) { -- 2.41.0
Hi Ronald,
kernel test robot noticed the following build warnings:
[auto build test WARNING on tty/tty-testing] [also build test WARNING on tty/tty-next tty/tty-linus usb/usb-testing usb/usb-next usb/usb-linus linus/master v6.6 next-20231031] [If your patch is applied to the wrong git tree, kindly drop us a note. And when submitting patch, we suggest to use '--base' as documented in https://git-scm.com/docs/git-format-patch#_base_tree_information]
url: https://github.com/intel-lab-lkp/linux/commits/Ronald-Wahl/serial-8250-8250_... base: https://git.kernel.org/pub/scm/linux/kernel/git/gregkh/tty.git tty-testing patch link: https://lore.kernel.org/r/20231031110950.11714-1-rwahl%40gmx.de patch subject: [PATCH v3] serial: 8250: 8250_omap: Do not start RX DMA on THRI interrupt config: mips-allmodconfig (https://download.01.org/0day-ci/archive/20231101/202311010816.kXNniDbT-lkp@i...) compiler: mips-linux-gcc (GCC) 13.2.0 reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20231101/202311010816.kXNniDbT-lkp@i...)
If you fix the issue in a separate patch/commit (i.e. not just a new version of the same patch/commit), kindly add following tags | Reported-by: kernel test robot lkp@intel.com | Closes: https://lore.kernel.org/oe-kbuild-all/202311010816.kXNniDbT-lkp@intel.com/
All warnings (new ones prefixed by >>):
drivers/tty/serial/8250/8250_omap.c: In function 'omap_8250_dma_handle_irq':
drivers/tty/serial/8250/8250_omap.c:1301:12: warning: suggest explicit braces to avoid ambiguous 'else' [-Wdangling-else]
1301 | if ((iir & 0x3f) != UART_IIR_THRI) | ^
vim +/else +1301 drivers/tty/serial/8250/8250_omap.c
1279 1280 /* 1281 * This is mostly serial8250_handle_irq(). We have a slightly different DMA 1282 * hoook for RX/TX and need different logic for them in the ISR. Therefore we 1283 * use the default routine in the non-DMA case and this one for with DMA. 1284 */ 1285 static int omap_8250_dma_handle_irq(struct uart_port *port) 1286 { 1287 struct uart_8250_port *up = up_to_u8250p(port); 1288 struct omap8250_priv *priv = up->port.private_data; 1289 u16 status; 1290 u8 iir; 1291 1292 iir = serial_port_in(port, UART_IIR); 1293 if (iir & UART_IIR_NO_INT) { 1294 return IRQ_HANDLED; 1295 } 1296 1297 uart_port_lock(port); 1298 1299 status = serial_port_in(port, UART_LSR); 1300
1301 if ((iir & 0x3f) != UART_IIR_THRI)
1302 if (priv->habit & UART_HAS_EFR2) 1303 am654_8250_handle_rx_dma(up, iir, status); 1304 else 1305 status = omap_8250_handle_rx_dma(up, iir, status); 1306 1307 serial8250_modem_status(up); 1308 if (status & UART_LSR_THRE && up->dma->tx_err) { 1309 if (uart_tx_stopped(&up->port) || 1310 uart_circ_empty(&up->port.state->xmit)) { 1311 up->dma->tx_err = 0; 1312 serial8250_tx_chars(up); 1313 } else { 1314 /* 1315 * try again due to an earlier failer which 1316 * might have been resolved by now. 1317 */ 1318 if (omap_8250_tx_dma(up)) 1319 serial8250_tx_chars(up); 1320 } 1321 } 1322 1323 uart_unlock_and_check_sysrq(port); 1324 1325 return 1; 1326 } 1327
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Ronald Wahl