From 419fa61f370072d82c037f84d8f89d0c4c23480b Mon Sep 17 00:00:00 2001 From: Yogesh Lal Date: Fri, 27 Jun 2014 12:07:51 +0530 Subject: libpayload: ipq808x: stale interrupt shall not be cleared unconditionally The serial driver hangs in cases when FIFO has more than single word to be processed. Easiest way to reproduce is to paste a string of greater than 4 characters in cli. Clearing the RXSTALE interrupt without draining all the characters from FIFO leads to the issue as the driver is dependent on msm_boot_uart_dm_read function to reinitialize for next transfer. Logically the driver is organized in such a manner that next transfer never gets initiated till rx_data_read < total_rx_data. Clearing the RXSTALE without consideration of total number of characters (or words) unprocessed makes the msm_boot_uart_dm_read to return on the first if conditional. Thus the driver is stuck forever. A quick fix is to avoid clearing the stale interrupt. Reset is handled whenever a new transfer is initialized in msm_boot_uart_dm_init_rx_transfer. BUG=chrome-os-partner:29542 TEST=manual -Paste a string greater than 4 characters in cli. Original-Change-Id: I016afb01a77cd14764f0176f6bf144fb29796c2f Original-Signed-off-by: Yogesh Lal Original-Reviewed-on: https://chromium-review.googlesource.com/209512 Original-Reviewed-by: Vadim Bendebury Original-Commit-Queue: Vadim Bendebury Original-Tested-by: Vadim Bendebury (cherry picked from commit 61528884ad2c0a8e146054bbfeb01a3bc73b9692) Signed-off-by: Marc Jones Change-Id: I936af5daa52a25f62133bdf9fb44f0b68cf34e88 Reviewed-on: http://review.coreboot.org/8667 Tested-by: build bot (Jenkins) Reviewed-by: Stefan Reinauer --- payloads/libpayload/drivers/serial/ipq806x.c | 3 --- 1 file changed, 3 deletions(-) (limited to 'payloads/libpayload/drivers') diff --git a/payloads/libpayload/drivers/serial/ipq806x.c b/payloads/libpayload/drivers/serial/ipq806x.c index 834389ec0e..912893d7e2 100644 --- a/payloads/libpayload/drivers/serial/ipq806x.c +++ b/payloads/libpayload/drivers/serial/ipq806x.c @@ -152,9 +152,6 @@ static unsigned msm_boot_uart_dm_read(void) return IPQ_UART_DM_E_RX_NOT_READY; } - /* Clear stale event. */ - writel(IPQ_UART_DM_CMD_RES_STALE_INT, IPQ_UART_DM_CR(base)); - /* Read UART_DM_RX_TOTAL_SNAP for actual number of bytes received */ if (total_rx_data == 0) total_rx_data = readl(IPQ_UART_DM_RX_TOTAL_SNAP(base)); -- cgit v1.2.3