During shutdown when a userspace service is disabled (which generates
an uart close), we got kernel crashes in the imx serial driver :
[ 1257.657423] Unhandled fault: external abort on non-linefetch (0x1008) at 0xf0938000
[ 1257.665122] pgd = ecf20000
[ 1257.667838] [f0938000] *pgd=de819811, *pte=53fc0653, *ppte=53fc0453
[ 1257.674179] Internal error: : 1008 [#1] SMP ARM
[ 1257.678722] Modules linked in:
[ 1257.681807] CPU: 0 PID: 3850 Comm: emerald_acq Not tainted 4.8.0 #10
[ 1257.688168] Hardware name: Freescale i.MX53 (Device Tree Support)
[ 1257.694269] task: e5c48000 task.stack: ed0b4000
[ 1257.698827] PC is at imx_rxint+0x5c/0x228
[ 1257.702859] LR is at lock_acquired+0x494/0x57c
[ 1257.707312] pc : [<80484884>] lr : [<80173aa0>] psr: 20070193
[ 1257.707312] sp : ed0b5c60 ip : ed0b5be8 fp : ed0b5c9c
[ 1257.718795] r10: 00000000 r9 : 00000000 r8 : 00000004
[ 1257.724027] r7 : 00000030 r6 : ee83e258 r5 : 00000000 r4 : ee09f410
[ 1257.730561] r3 : 0015c30c r2 : f0938000 r1 : 00000135 r0 : 40070193
[ 1257.737099] Flags: nzCv IRQs off FIQs on Mode SVC_32 ISA ARM Segment none
[ 1257.744327] Control: 10c5387d Table: dcf20019 DAC: 00000051
[ 1257.750080] Process emerald_acq (pid: 3850, stack limit = 0xed0b4210)
[ 1257.756527] Stack: (0xed0b5c60 to 0xed0b6000)
[ 1257.760898] 5c60: ed0b5cf4 40070193 80175f64 80faf384 e5c484c0 ee09f410 00007240 00005099
[ 1257.769087] 5c80: 00000030 00000030 80e025c4 00000000 ed0b5cf4 ed0b5ca0 80485b18 80484834
[ 1257.777275] 5ca0: 8012fe26 00000000 00000000 60070193 ee81b210 00000001 ed0b5cdc ed0b5cc8
[ 1257.785463] 5cc0: 80171d28 80171c3c 80e2d634 ee096740 ee81b200 ee81b210 00000001 00000030
[ 1257.793651] 5ce0: 80e025c4 00000000 ed0b5d34 ed0b5cf8 80182f10 804857fc e5c484c0 00000002
[ 1257.801839] 5d00: ee81b200 ed0b5d3c 60070193 ee81b200 ee81b200 ee81b210 00000001 ee81c400
[ 1257.810027] 5d20: 00000001 00000008 ed0b5d54 ed0b5d38 801832d8 80182ed0 808f4b60 00000000
[ 1257.818216] 5d40: ee81b200 ee81b260 ed0b5d74 ed0b5d58 8018335c 801832b8 ee81b200 ee81b260
[ 1257.826404] 5d60: ee81b210 00000001 ed0b5d94 ed0b5d78 80186ba0 80183320 80debe8c 00000030
[ 1257.834592] 5d80: 00000000 00000001 ed0b5da4 ed0b5d98 80182420 80186af4 ed0b5dcc ed0b5da8
[ 1257.842780] 5da0: 801827a0 801823fc 00000000 80e8350c 00000020 00000001 ed0b5df8 00000001
[ 1257.850968] 5dc0: ed0b5df4 ed0b5dd0 80101530 8018274c 808f4bec 20070013 ffffffff ed0b5e2c
[ 1257.859156] 5de0: ee09f410 ed0b4000 ed0b5e5c ed0b5df8 808f55f0 801014c8 00000001 00000130
[ 1257.867345] 5e00: 00000000 e5c48000 60070013 ee09f410 00000000 60070013 ee09f410 ed06a640
[ 1257.875533] 5e20: 00000008 ed0b5e5c ed0b5df0 ed0b5e48 801756a8 808f4bec 20070013 ffffffff
[ 1257.883722] 5e40: 00000051 7f000000 ee09f410 00000b01 ed0b5e7c ed0b5e60 80485d74 808f4bb4
[ 1257.891912] 5e60: ee83e258 ee09f410 ee83e3a4 80e2d634 ed0b5ea4 ed0b5e80 8047f514 80485c70
[ 1257.900100] 5e80: ee83e258 ed375000 ee09f410 ee83e310 ee83e3ac ed06a640 ed0b5ecc ed0b5ea8
[ 1257.908288] 5ea0: 80481304 8047f400 ed375000 eeabce60 00000000 ee7973e8 00000000 ed06a640
[ 1257.916477] 5ec0: ed0b5f14 ed0b5ed0 80462fe0 804811ac 00000008 eeabce60 00000001 00000001
[ 1257.924665] 5ee0: 00000000 802713dc ed0b5f54 ed06a640 eeabce60 ee2c6910 ee7973e8 00000000
[ 1257.932854] 5f00: eeabce60 00000008 ed0b5f54 ed0b5f18 80271404 80462ee8 00000000 00000000
[ 1257.941044] 5f20: ed06c640 ed06a648 ed0b5f4c e5c48400 00000000 80e84054 e5c48440 e5c48000
[ 1257.949232] 5f40: 00000000 00000000 ed0b5f64 ed0b5f58 802715c4 80271378 ed0b5f8c ed0b5f68
[ 1257.957420] 5f60: 80146034 802715b8 00000000 ed0b4000 ed0b5fb0 801086c4 801086c4 ed0b4000
[ 1257.965610] 5f80: ed0b5fac ed0b5f90 8010cc68 80145f78 0054756c 00000000 767474b4 00000006
[ 1257.973798] 5fa0: 00000000 ed0b5fb0 80108548 8010cbc4 00000000 76f2a084 00000002 00000000
[ 1257.981986] 5fc0: 0054756c 00000000 767474b4 00000006 0225e880 00000000 76f36000 7e836d34
[ 1257.990175] 5fe0: 00000000 7e836d10 76f2a4c0 76a5db68 80070010 00000062 00000000 00000000
[ 1257.998357] Backtrace:
[ 1258.000837] [<80484828>] (imx_rxint) from [<80485b18>] (imx_int+0x328/0x474)
[ 1258.007892] r10:00000000 r9:80e025c4 r8:00000030 r7:00000030 r6:00005099 r5:00007240
[ 1258.015815] r4:ee09f410
[ 1258.018386] [<804857f0>] (imx_int) from [<80182f10>] (__handle_irq_event_percpu+0x4c/0x3e8)
[ 1258.026742] r10:00000000 r9:80e025c4 r8:00000030 r7:00000001 r6:ee81b210 r5:ee81b200
[ 1258.034664] r4:ee096740
[ 1258.037226] [<80182ec4>] (__handle_irq_event_percpu) from [<801832d8>] (handle_irq_event_percpu+0x2c/0x68)
[ 1258.046885] r10:00000008 r9:00000001 r8:ee81c400 r7:00000001 r6:ee81b210 r5:ee81b200
[ 1258.054806] r4:ee81b200
[ 1258.057369] [<801832ac>] (handle_irq_event_percpu) from [<8018335c>] (handle_irq_event+0x48/0x6c)
[ 1258.066246] r5:ee81b260 r4:ee81b200
[ 1258.069866] [<80183314>] (handle_irq_event) from [<80186ba0>] (handle_level_irq+0xb8/0x154)
[ 1258.078222] r7:00000001 r6:ee81b210 r5:ee81b260 r4:ee81b200
[ 1258.083961] [<80186ae8>] (handle_level_irq) from [<80182420>] (generic_handle_irq+0x30/0x44)
[ 1258.092404] r7:00000001 r6:00000000 r5:00000030 r4:80debe8c
[ 1258.098143] [<801823f0>] (generic_handle_irq) from [<801827a0>] (__handle_domain_irq+0x60/0xc8)
[ 1258.106854] [<80182740>] (__handle_domain_irq) from [<80101530>] (tzic_handle_irq+0x74/0x9c)
[ 1258.115297] r9:00000001 r8:ed0b5df8 r7:00000001 r6:00000020 r5:80e8350c r4:00000000
[ 1258.123139] [<801014bc>] (tzic_handle_irq) from [<808f55f0>] (__irq_svc+0x70/0x98)
[ 1258.130715] Exception stack(0xed0b5df8 to 0xed0b5e40)
[ 1258.135773] 5de0: 00000001 00000130
[ 1258.143962] 5e00: 00000000 e5c48000 60070013 ee09f410 00000000 60070013 ee09f410 ed06a640
[ 1258.152151] 5e20: 00000008 ed0b5e5c ed0b5df0 ed0b5e48 801756a8 808f4bec 20070013 ffffffff
[ 1258.160333] r9:ed0b4000 r8:ee09f410 r7:ed0b5e2c r6:ffffffff r5:20070013 r4:808f4bec
[ 1258.168188] [<808f4ba8>] (_raw_spin_unlock_irqrestore) from [<80485d74>] (imx_shutdown+0x110/0x214)
[ 1258.177239] r5:00000b01 r4:ee09f410
[ 1258.180860] [<80485c64>] (imx_shutdown) from [<8047f514>] (uart_shutdown+0x120/0x17c)
[ 1258.188695] r7:80e2d634 r6:ee83e3a4 r5:ee09f410 r4:ee83e258
[ 1258.194434] [<8047f3f4>] (uart_shutdown) from [<80481304>] (uart_close+0x164/0x254)
[ 1258.202096] r9:ed06a640 r8:ee83e3ac r7:ee83e310 r6:ee09f410 r5:ed375000 r4:ee83e258
[ 1258.209948] [<804811a0>] (uart_close) from [<80462fe0>] (tty_release+0x104/0x498)
[ 1258.217439] r9:ed06a640 r8:00000000 r7:ee7973e8 r6:00000000 r5:eeabce60 r4:ed375000
[ 1258.225285] [<80462edc>] (tty_release) from [<80271404>] (__fput+0x98/0x1e8)
[ 1258.232339] r10:00000008 r9:eeabce60 r8:00000000 r7:ee7973e8 r6:ee2c6910 r5:eeabce60
[ 1258.240261] r4:ed06a640
[ 1258.242823] [<8027136c>] (__fput) from [<802715c4>] (____fput+0x18/0x1c)
[ 1258.249528] r10:00000000 r9:00000000 r8:e5c48000 r7:e5c48440 r6:80e84054 r5:00000000
[ 1258.257450] r4:e5c48400
[ 1258.260021] [<802715ac>] (____fput) from [<80146034>] (task_work_run+0xc8/0xf8)
[ 1258.267352] [<80145f6c>] (task_work_run) from [<8010cc68>] (do_work_pending+0xb0/0xd0)
[ 1258.275274] r9:ed0b4000 r8:801086c4 r7:801086c4 r6:ed0b5fb0 r5:ed0b4000 r4:00000000
[ 1258.283116] [<8010cbb8>] (do_work_pending) from [<80108548>] (slow_work_pending+0xc/0x20)
[ 1258.291298] r7:00000006 r6:767474b4 r5:00000000 r4:0054756c
[ 1258.297037] Code: e5943094 e594202c e2833001 e5843094 (e592a000)
[ 1258.303148] ---[ end trace 7a50198148a54c4d ]---
[ 1258.307776] Kernel panic - not syncing: Fatal exception in interrupt
[ 1258.314160] ---[ end Kernel panic - not syncing: Fatal exception in interrupt
After investigations, we found several issues:
It looks that interrupts can happen after the dma was disabled and
port was not yet shutdown. This will result in interrupts handled by
imx_rxint. Analyzed the imx_shutdown function, and found that:
- Some interrupts were not disabled during shutdown (AWAKEN, UCR4_OREN,
UCR1_TRDYEN)
- TX was not stopped in all situations (if dma is enabled and
transmitting)
- Using deprecated dmaengine_terminate_all method.
- Trying to close DMA channels several times.
This set of patches proposes fix regarding these issues and problems we
found during debugging.
Changes in v2:
- Re-worked assignment of `dma_is_rxing` in patch 1/7
- Removed commit "serial: imx: move log from error to debug type"
- Removed commit "serial: imx: init dma_is_{rx|tx}ing variables"
- Improved commit log for "serial: imx: Simplify DMA disablement"
and splitted it in two commits, with one for CTSC and CTS
- Added commit "serial: imx: remove CTSC and CTS handling"
- Fixed typo in commit "unmap sg buffers when DMA channel is released"
- Re-worded commit log for "serial: imx: update the stop rx,tx procedures" and
removed forward declaration
- Fixed typo in commit "serial: imx: Fix imx_shutdown procedure" and simplified
locking
Nandor Han (6):
serial: imx: only set DMA rx-ing when DMA starts
serial: imx: Simplify DMA disablement
serial: imx: remove CTSC and CTS handling
serial: imx: unmap sg buffers when DMA channel is released
serial: imx: update the stop rx,tx procedures
serial: imx: Fix imx_shutdown procedure
drivers/tty/serial/imx.c | 116 ++++++++++++++++++++++++++---------------------
1 file changed, 65 insertions(+), 51 deletions(-)
--
1.8.3.1
From: Nandor Han <[email protected]>
This commits simplify the function imx_disable_dma() by moving
the code for disabling RX and TX DMAs to dedicated functions.
This is a preparation for the next commit.
Signed-off-by: Nandor Han <[email protected]>
Signed-off-by: Romain Perier <[email protected]>
---
drivers/tty/serial/imx.c | 26 ++++++++++++++++++++------
1 file changed, 20 insertions(+), 6 deletions(-)
diff --git a/drivers/tty/serial/imx.c b/drivers/tty/serial/imx.c
index 01df430..5291b86 100644
--- a/drivers/tty/serial/imx.c
+++ b/drivers/tty/serial/imx.c
@@ -360,6 +360,24 @@ static void imx_port_rts_auto(struct imx_port *sport, unsigned long *ucr2)
*ucr2 |= UCR2_CTSC;
}
+static void imx_stop_tx_dma(struct imx_port *sport)
+{
+ unsigned long temp;
+
+ temp = readl(sport->port.membase + UCR1);
+ temp &= ~UCR1_TDMAEN;
+ writel(temp, sport->port.membase + UCR1);
+}
+
+static void imx_stop_rx_dma(struct imx_port *sport)
+{
+ unsigned long temp;
+
+ temp = readl(sport->port.membase + UCR1);
+ temp &= ~(UCR1_RDMAEN | UCR1_ATDMAEN);
+ writel(temp, sport->port.membase + UCR1);
+}
+
/*
* interrupts disabled on entry
*/
@@ -1228,12 +1246,8 @@ static void imx_enable_dma(struct imx_port *sport)
static void imx_disable_dma(struct imx_port *sport)
{
- unsigned long temp;
-
- /* clear UCR1 */
- temp = readl(sport->port.membase + UCR1);
- temp &= ~(UCR1_RDMAEN | UCR1_TDMAEN | UCR1_ATDMAEN);
- writel(temp, sport->port.membase + UCR1);
+ imx_stop_rx_dma(sport);
+ imx_stop_tx_dma(sport);
/* clear UCR2 */
temp = readl(sport->port.membase + UCR2);
--
1.8.3.1
From: Nandor Han <[email protected]>
This commits unmaps sg buffers when the DMA channel is released. It also
sets to zero `dma_is_rxing` and `dma_is_txing` to state that the
corresponding channels cannot transmit/receive data, as these are
disabled.
Signed-off-by: Nandor Han <[email protected]>
Signed-off-by: Romain Perier <[email protected]>
---
drivers/tty/serial/imx.c | 12 ++++++++++++
1 file changed, 12 insertions(+)
diff --git a/drivers/tty/serial/imx.c b/drivers/tty/serial/imx.c
index dd3ebb4..3112d88 100644
--- a/drivers/tty/serial/imx.c
+++ b/drivers/tty/serial/imx.c
@@ -367,6 +367,12 @@ static void imx_stop_tx_dma(struct imx_port *sport)
temp = readl(sport->port.membase + UCR1);
temp &= ~UCR1_TDMAEN;
writel(temp, sport->port.membase + UCR1);
+
+ if (sport->dma_is_txing) {
+ dma_unmap_sg(sport->port.dev, &sport->tx_sgl[0],
+ sport->dma_tx_nents, DMA_TO_DEVICE);
+ sport->dma_is_txing = 0;
+ }
}
static void imx_stop_rx_dma(struct imx_port *sport)
@@ -376,6 +382,12 @@ static void imx_stop_rx_dma(struct imx_port *sport)
temp = readl(sport->port.membase + UCR1);
temp &= ~(UCR1_RDMAEN | UCR1_ATDMAEN);
writel(temp, sport->port.membase + UCR1);
+
+ if (sport->dma_is_rxing) {
+ dma_unmap_sg(sport->port.dev, &sport->rx_sgl, 1,
+ DMA_FROM_DEVICE);
+ sport->dma_is_rxing = 0;
+ }
}
/*
--
1.8.3.1
From: Nandor Han <[email protected]>
According to "Documentation/serial/driver" both procedures should stop
receiving or sending data. Based on this the procedures should stop the
activity regardless if DMA is enabled or not.
This commit updates both imx_stop_{rx|tx} procedures to stop the
activity and disable the interrupts related to that.
Signed-off-by: Nandor Han <[email protected]>
Signed-off-by: Romain Perier <[email protected]>
---
drivers/tty/serial/imx.c | 36 +++++++++++++++++-------------------
1 file changed, 17 insertions(+), 19 deletions(-)
diff --git a/drivers/tty/serial/imx.c b/drivers/tty/serial/imx.c
index 3112d88..d35112f 100644
--- a/drivers/tty/serial/imx.c
+++ b/drivers/tty/serial/imx.c
@@ -398,15 +398,14 @@ static void imx_stop_tx(struct uart_port *port)
struct imx_port *sport = (struct imx_port *)port;
unsigned long temp;
- /*
- * We are maybe in the SMP context, so if the DMA TX thread is running
- * on other cpu, we have to wait for it to finish.
- */
- if (sport->dma_is_enabled && sport->dma_is_txing)
- return;
+ sport->tx_bytes = 0;
+
+ if (sport->dma_is_enabled)
+ imx_stop_tx_dma(sport);
temp = readl(port->membase + UCR1);
- writel(temp & ~UCR1_TXMPTYEN, port->membase + UCR1);
+ temp &= ~(UCR1_TXMPTYEN | UCR1_TRDYEN | UCR1_RTSDEN);
+ writel(temp, port->membase + UCR1);
/* in rs485 mode disable transmitter if shifter is empty */
if (port->rs485.flags & SER_RS485_ENABLED &&
@@ -433,21 +432,20 @@ static void imx_stop_rx(struct uart_port *port)
struct imx_port *sport = (struct imx_port *)port;
unsigned long temp;
- if (sport->dma_is_enabled && sport->dma_is_rxing) {
- if (sport->port.suspended) {
- dmaengine_terminate_all(sport->dma_chan_rx);
- sport->dma_is_rxing = 0;
- } else {
- return;
- }
- }
+ if (sport->dma_is_enabled)
+ imx_stop_rx_dma(sport);
+
+ temp = readl(sport->port.membase + UCR1);
+ temp &= ~UCR1_RRDYEN;
+ writel(temp, sport->port.membase + UCR1);
temp = readl(sport->port.membase + UCR2);
- writel(temp & ~UCR2_RXEN, sport->port.membase + UCR2);
+ temp &= ~UCR2_ATEN;
+ writel(temp, sport->port.membase + UCR2);
- /* disable the `Receiver Ready Interrrupt` */
- temp = readl(sport->port.membase + UCR1);
- writel(temp & ~UCR1_RRDYEN, sport->port.membase + UCR1);
+ temp = readl(sport->port.membase + UCR3);
+ temp &= ~UCR3_AWAKEN;
+ writel(temp, sport->port.membase + UCR3);
}
/*
--
1.8.3.1
From: Nandor Han <[email protected]>
In some cases, it looks that interrupts can happen after the dma was
disabled and port was not yet shutdown. This will result in interrupts
handled by imx_rxint.
This commits updates the shutdown function to ensure that underlying
components are disabled in the right order. This disables RX and TX
blocks, then it disabled interrupts. In case DMA is enabled, it disables
DMA and free corresponding resources. It disables UART port and stop
clocks.
Signed-off-by: Nandor Han <[email protected]>
Signed-off-by: Romain Perier <[email protected]>
---
drivers/tty/serial/imx.c | 34 +++++++++++++++-------------------
1 file changed, 15 insertions(+), 19 deletions(-)
diff --git a/drivers/tty/serial/imx.c b/drivers/tty/serial/imx.c
index d35112f..bfe7180 100644
--- a/drivers/tty/serial/imx.c
+++ b/drivers/tty/serial/imx.c
@@ -1396,44 +1396,40 @@ static void imx_shutdown(struct uart_port *port)
unsigned long temp;
unsigned long flags;
- if (sport->dma_is_enabled) {
- sport->dma_is_rxing = 0;
- sport->dma_is_txing = 0;
- dmaengine_terminate_sync(sport->dma_chan_tx);
- dmaengine_terminate_sync(sport->dma_chan_rx);
-
+ if (!sport->port.suspended) {
spin_lock_irqsave(&sport->port.lock, flags);
imx_stop_tx(port);
imx_stop_rx(port);
- imx_disable_dma(sport);
+
+ if (sport->dma_is_inited && sport->dma_is_enabled)
+ imx_disable_dma(sport);
+
spin_unlock_irqrestore(&sport->port.lock, flags);
imx_uart_dma_exit(sport);
}
- mctrl_gpio_disable_ms(sport->gpios);
-
spin_lock_irqsave(&sport->port.lock, flags);
temp = readl(sport->port.membase + UCR2);
- temp &= ~(UCR2_TXEN);
+ temp &= ~(UCR2_TXEN | UCR2_RXEN);
writel(temp, sport->port.membase + UCR2);
+ temp = readl(sport->port.membase + UCR4);
+ temp &= ~UCR4_OREN;
+ writel(temp, sport->port.membase + UCR4);
spin_unlock_irqrestore(&sport->port.lock, flags);
- /*
- * Stop our timer.
- */
- del_timer_sync(&sport->timer);
+ mctrl_gpio_disable_ms(sport->gpios);
- /*
- * Disable all interrupts, port and break condition.
- */
+ /* Stop our timer. */
+ del_timer_sync(&sport->timer);
+ /* Disable port. */
spin_lock_irqsave(&sport->port.lock, flags);
temp = readl(sport->port.membase + UCR1);
- temp &= ~(UCR1_TXMPTYEN | UCR1_RRDYEN | UCR1_RTSDEN | UCR1_UARTEN);
-
+ temp &= ~UCR1_UARTEN;
writel(temp, sport->port.membase + UCR1);
spin_unlock_irqrestore(&sport->port.lock, flags);
+ /* Disable clocks. */
clk_disable_unprepare(sport->clk_per);
clk_disable_unprepare(sport->clk_ipg);
}
--
1.8.3.1
From: Nandor Han <[email protected]>
Avoid the situation when `dma_is_rxing` could incorrectly signal that
DMA RX channel is receiving data in case DMA preparation or sg mapping
fails.
This commit fixes the issues by moving the assignment of dma_is_rxing
out of imx_disable_rx_int(), then the variable is set to 1 from
start_rx_dma() only when the preparation is correctly done.
Signed-off-by: Nandor Han <[email protected]>
Signed-off-by: Romain Perier <[email protected]>
---
drivers/tty/serial/imx.c | 3 +--
1 file changed, 1 insertion(+), 2 deletions(-)
diff --git a/drivers/tty/serial/imx.c b/drivers/tty/serial/imx.c
index 3bae4ea..01df430 100644
--- a/drivers/tty/serial/imx.c
+++ b/drivers/tty/serial/imx.c
@@ -729,8 +729,6 @@ static void imx_disable_rx_int(struct imx_port *sport)
{
unsigned long temp;
- sport->dma_is_rxing = 1;
-
/* disable the receiver ready and aging timer interrupts */
temp = readl(sport->port.membase + UCR1);
temp &= ~(UCR1_RRDYEN);
@@ -1083,6 +1081,7 @@ static int start_rx_dma(struct imx_port *sport)
desc->callback_param = sport;
dev_dbg(dev, "RX: prepare for the DMA.\n");
+ sport->dma_is_rxing = 1;
sport->rx_cookie = dmaengine_submit(desc);
dma_async_issue_pending(chan);
return 0;
--
1.8.3.1
From: Nandor Han <[email protected]>
CTSC and CTS are not related to DMA and might add
disruption in some cases.
Signed-off-by: Romain Perier <[email protected]>
---
drivers/tty/serial/imx.c | 5 -----
1 file changed, 5 deletions(-)
diff --git a/drivers/tty/serial/imx.c b/drivers/tty/serial/imx.c
index 5291b86..dd3ebb4 100644
--- a/drivers/tty/serial/imx.c
+++ b/drivers/tty/serial/imx.c
@@ -1249,11 +1249,6 @@ static void imx_disable_dma(struct imx_port *sport)
imx_stop_rx_dma(sport);
imx_stop_tx_dma(sport);
- /* clear UCR2 */
- temp = readl(sport->port.membase + UCR2);
- temp &= ~(UCR2_CTSC | UCR2_CTS | UCR2_ATEN);
- writel(temp, sport->port.membase + UCR2);
-
imx_setup_ufcr(sport, TXTL_DEFAULT, RXTL_DEFAULT);
sport->dma_is_enabled = 0;
--
1.8.3.1
Hello,
On Wed, Jul 05, 2017 at 03:07:01PM +0200, Romain Perier wrote:
> From: Nandor Han <[email protected]>
>
> Avoid the situation when `dma_is_rxing` could incorrectly signal that
> DMA RX channel is receiving data in case DMA preparation or sg mapping
> fails.
>
> This commit fixes the issues by moving the assignment of dma_is_rxing
> out of imx_disable_rx_int(), then the variable is set to 1 from
> start_rx_dma() only when the preparation is correctly done.
I'd write:
There are a few issues with setting dma_is_rxing to 1 in
imx_disable_rx_int:
- Currently always after imx_disable_rx_int() the function
start_rx_dma() is called. This dependency isn't obvious though.
- start_rx_dma() does error checking and might exit without enabling
DMA but keeping dma_is_rxing 1.
So the more natural place for setting dma_is_rxing to 1 is in
start_rx_dma after all errors are checked.
If you use this, there is nothing left of Nandor Han's patch and you can
drop his authorship.
Best regards
Uwe
--
Pengutronix e.K. | Uwe Kleine-K?nig |
Industrial Linux Solutions | http://www.pengutronix.de/ |
Cc += Clemens Gruber + Fabio Estevam
On Wed, Jul 05, 2017 at 03:07:03PM +0200, Romain Perier wrote:
> From: Nandor Han <[email protected]>
>
> CTSC and CTS are not related to DMA and might add
> disruption in some cases.
>
> Signed-off-by: Romain Perier <[email protected]>
If it was Nandor Han who created this patch, it would be great to get
his sob. If it was you, drop the From: line above.
> ---
> drivers/tty/serial/imx.c | 5 -----
> 1 file changed, 5 deletions(-)
>
> diff --git a/drivers/tty/serial/imx.c b/drivers/tty/serial/imx.c
> index 5291b86..dd3ebb4 100644
> --- a/drivers/tty/serial/imx.c
> +++ b/drivers/tty/serial/imx.c
> @@ -1249,11 +1249,6 @@ static void imx_disable_dma(struct imx_port *sport)
> imx_stop_rx_dma(sport);
> imx_stop_tx_dma(sport);
>
> - /* clear UCR2 */
> - temp = readl(sport->port.membase + UCR2);
> - temp &= ~(UCR2_CTSC | UCR2_CTS | UCR2_ATEN);
> - writel(temp, sport->port.membase + UCR2);
> -
Before this patch imx_disable_dma resulted in the #CTS pin being high
(inactive).
Does this qualify as a fix? If so, you should sort this patch to the
beginning of the series. Did you do test this patch and its effects
separately?
@Clemens: maybe this patch makes a relevant difference when the port is
operated in rs485 mode. Do you care to test?
> imx_setup_ufcr(sport, TXTL_DEFAULT, RXTL_DEFAULT);
>
> sport->dma_is_enabled = 0;
> --
> 1.8.3.1
Best regards
Uwe
--
Pengutronix e.K. | Uwe Kleine-K?nig |
Industrial Linux Solutions | http://www.pengutronix.de/ |
Hi,
On Wed, Jul 05, 2017 at 03:38:45PM +0200, Uwe Kleine-K?nig wrote:
> Cc += Clemens Gruber + Fabio Estevam
>
> On Wed, Jul 05, 2017 at 03:07:03PM +0200, Romain Perier wrote:
> > From: Nandor Han <[email protected]>
> >
> > CTSC and CTS are not related to DMA and might add
> > disruption in some cases.
> >
> > Signed-off-by: Romain Perier <[email protected]>
>
> If it was Nandor Han who created this patch, it would be great to get
> his sob. If it was you, drop the From: line above.
>
> > ---
> > drivers/tty/serial/imx.c | 5 -----
> > 1 file changed, 5 deletions(-)
> >
> > diff --git a/drivers/tty/serial/imx.c b/drivers/tty/serial/imx.c
> > index 5291b86..dd3ebb4 100644
> > --- a/drivers/tty/serial/imx.c
> > +++ b/drivers/tty/serial/imx.c
> > @@ -1249,11 +1249,6 @@ static void imx_disable_dma(struct imx_port *sport)
> > imx_stop_rx_dma(sport);
> > imx_stop_tx_dma(sport);
> >
> > - /* clear UCR2 */
> > - temp = readl(sport->port.membase + UCR2);
> > - temp &= ~(UCR2_CTSC | UCR2_CTS | UCR2_ATEN);
> > - writel(temp, sport->port.membase + UCR2);
> > -
>
> Before this patch imx_disable_dma resulted in the #CTS pin being high
> (inactive).
>
> Does this qualify as a fix? If so, you should sort this patch to the
> beginning of the series. Did you do test this patch and its effects
> separately?
>
> @Clemens: maybe this patch makes a relevant difference when the port is
> operated in rs485 mode. Do you care to test?
I just finished testing it. The results are about the same as with v1 of
this patch series:
Applying v2 of patch 1/6, 2/6 and 3/6 (or even 3/6 alone) does not fix
the RS-485 DMA bug. It behaves exactly the same as without these
patches, meaning the whole xmit circ_buf (UART_XMIT_SIZE bytes) is sent
out, as seen in the logic analyzer screenshots from my first bug report:
https://pqgruber.com/rs485_results.png
Applying the whole series does make a (small) difference though:
The first few transmissions after a fresh boot work correctly! However,
after a few transmissions, characters are sent out twice and longer
transmissions are garbled, although not in the same way as before. The
whole circ_buf is no longer sent out.
With all patches from this series applied, I see the following on the
logic analyzer, when calling "echo Test > /dev/ttymxc4":
https://pqgruber.com/rs485txtest.png
(This pattern is not always the same, sometimes it is TeTesstt\n\n,
sometimes TeTesst\nt\n or TeTsestt\n\n and so on)
This behavior is reproducible on i.MX6Q and i.MX6D, not on i.MX6S/etc.,
I therefore assume that it is a SMP-/locking-related problem.
I will try to debug this further, and verify if - with this series
applied - xmit->tail is still jumping over xmit->head. And when exactly
this is happening.
Help is much appreciated!
Best regards,
Clemens
Hello,
Le 05/07/2017 à 15:29, Uwe Kleine-König a écrit :
> Hello,
>
> On Wed, Jul 05, 2017 at 03:07:01PM +0200, Romain Perier wrote:
>> From: Nandor Han <[email protected]>
>>
>> Avoid the situation when `dma_is_rxing` could incorrectly signal that
>> DMA RX channel is receiving data in case DMA preparation or sg mapping
>> fails.
>>
>> This commit fixes the issues by moving the assignment of dma_is_rxing
>> out of imx_disable_rx_int(), then the variable is set to 1 from
>> start_rx_dma() only when the preparation is correctly done.
> I'd write:
>
> There are a few issues with setting dma_is_rxing to 1 in
> imx_disable_rx_int:
>
> - Currently always after imx_disable_rx_int() the function
> start_rx_dma() is called. This dependency isn't obvious though.
> - start_rx_dma() does error checking and might exit without enabling
> DMA but keeping dma_is_rxing 1.
>
> So the more natural place for setting dma_is_rxing to 1 is in
> start_rx_dma after all errors are checked.
>
> If you use this, there is nothing left of Nandor Han's patch and you can
> drop his authorship.
>
> Best regards
> Uwe
>
Ok, will do. No other feedback for the rest of the series ? (just to
know if I send a v3 or If I wait a bit...)
Thanks,
Romain
On Thu, Jul 06, 2017 at 10:31:38AM +0200, Romain Perier wrote:
> Hello,
>
>
> Le 05/07/2017 ? 15:29, Uwe Kleine-K?nig a ?crit :
> > Hello,
> >
> > On Wed, Jul 05, 2017 at 03:07:01PM +0200, Romain Perier wrote:
> >> From: Nandor Han <[email protected]>
> >>
> >> Avoid the situation when `dma_is_rxing` could incorrectly signal that
> >> DMA RX channel is receiving data in case DMA preparation or sg mapping
> >> fails.
> >>
> >> This commit fixes the issues by moving the assignment of dma_is_rxing
> >> out of imx_disable_rx_int(), then the variable is set to 1 from
> >> start_rx_dma() only when the preparation is correctly done.
> > I'd write:
> >
> > There are a few issues with setting dma_is_rxing to 1 in
> > imx_disable_rx_int:
> >
> > - Currently always after imx_disable_rx_int() the function
> > start_rx_dma() is called. This dependency isn't obvious though.
> > - start_rx_dma() does error checking and might exit without enabling
> > DMA but keeping dma_is_rxing 1.
> >
> > So the more natural place for setting dma_is_rxing to 1 is in
> > start_rx_dma after all errors are checked.
> >
> > If you use this, there is nothing left of Nandor Han's patch and you can
> > drop his authorship.
> >
> > Best regards
> > Uwe
> >
> Ok, will do. No other feedback for the rest of the series ? (just to
> know if I send a v3 or If I wait a bit...)
I didn't come around looking in the patches I didn't comment yet.
Best regards
Uwe
--
Pengutronix e.K. | Uwe Kleine-K?nig |
Industrial Linux Solutions | http://www.pengutronix.de/ |
Hi Nandor,
[auto build test ERROR on tty/tty-testing]
[also build test ERROR on v4.12 next-20170706]
[if your patch is applied to the wrong git tree, please drop us a note to help improve the system]
url: https://github.com/0day-ci/linux/commits/Romain-Perier/serial-imx-various-improvements/20170706-153226
base: https://git.kernel.org/pub/scm/linux/kernel/git/gregkh/tty.git tty-testing
config: arm-multi_v5_defconfig (attached as .config)
compiler: arm-linux-gnueabi-gcc (Debian 6.1.1-9) 6.1.1 20160705
reproduce:
wget https://raw.githubusercontent.com/01org/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
chmod +x ~/bin/make.cross
# save the attached .config to linux build tree
make.cross ARCH=arm
Note: the linux-review/Romain-Perier/serial-imx-various-improvements/20170706-153226 HEAD c99e6e0fd195719d99b5ce9a4f9a155243772578 builds fine.
It only hurts bisectibility.
All errors (new ones prefixed by >>):
drivers/tty/serial/imx.c: In function 'imx_disable_dma':
>> drivers/tty/serial/imx.c:1250:2: error: 'temp' undeclared (first use in this function)
temp = readl(sport->port.membase + UCR2);
^~~~
drivers/tty/serial/imx.c:1250:2: note: each undeclared identifier is reported only once for each function it appears in
vim +/temp +1250 drivers/tty/serial/imx.c
b4cdc8f6 Huang Shijie 2013-07-08 1244 static void imx_disable_dma(struct imx_port *sport)
b4cdc8f6 Huang Shijie 2013-07-08 1245 {
52fe0ee0 Nandor Han 2017-07-05 1246 imx_stop_rx_dma(sport);
52fe0ee0 Nandor Han 2017-07-05 1247 imx_stop_tx_dma(sport);
b4cdc8f6 Huang Shijie 2013-07-08 1248
b4cdc8f6 Huang Shijie 2013-07-08 1249 /* clear UCR2 */
b4cdc8f6 Huang Shijie 2013-07-08 @1250 temp = readl(sport->port.membase + UCR2);
86a04ba6 Lucas Stach 2015-09-04 1251 temp &= ~(UCR2_CTSC | UCR2_CTS | UCR2_ATEN);
b4cdc8f6 Huang Shijie 2013-07-08 1252 writel(temp, sport->port.membase + UCR2);
b4cdc8f6 Huang Shijie 2013-07-08 1253
:::::: The code at line 1250 was first introduced by commit
:::::: b4cdc8f61beb2a55c8c3d22dfcaf5f34a919fe9b serial: imx: add DMA support for imx6q
:::::: TO: Huang Shijie <[email protected]>
:::::: CC: Greg Kroah-Hartman <[email protected]>
---
0-DAY kernel test infrastructure Open Source Technology Center
https://lists.01.org/pipermail/kbuild-all Intel Corporation
Hi
On Wed, Jul 05, 2017 at 03:38:45PM +0200, Uwe Kleine-K?nig wrote:
> Cc += Clemens Gruber + Fabio Estevam
>
> On Wed, Jul 05, 2017 at 03:07:03PM +0200, Romain Perier wrote:
> > From: Nandor Han <[email protected]>
> >
> > CTSC and CTS are not related to DMA and might add
> > disruption in some cases.
> >
> > Signed-off-by: Romain Perier <[email protected]>
>
> If it was Nandor Han who created this patch, it would be great to get
> his sob. If it was you, drop the From: line above.
>
This patch was broken out from a larger one written by Nandor, who is
happy for me to add his sob.
> > ---
> > drivers/tty/serial/imx.c | 5 -----
> > 1 file changed, 5 deletions(-)
> >
> > diff --git a/drivers/tty/serial/imx.c b/drivers/tty/serial/imx.c
> > index 5291b86..dd3ebb4 100644
> > --- a/drivers/tty/serial/imx.c
> > +++ b/drivers/tty/serial/imx.c
> > @@ -1249,11 +1249,6 @@ static void imx_disable_dma(struct imx_port *sport)
> > imx_stop_rx_dma(sport);
> > imx_stop_tx_dma(sport);
> >
> > - /* clear UCR2 */
> > - temp = readl(sport->port.membase + UCR2);
> > - temp &= ~(UCR2_CTSC | UCR2_CTS | UCR2_ATEN);
> > - writel(temp, sport->port.membase + UCR2);
> > -
>
> Before this patch imx_disable_dma resulted in the #CTS pin being high
> (inactive).
>
> Does this qualify as a fix? If so, you should sort this patch to the
> beginning of the series. Did you do test this patch and its effects
> separately?
>
I've been giving the RTS/CTS lines a bit of a kick with (and without) this
patch and I'm seeing what I'd expect to see on the CTS pin (the Wandboard
I'm using runs this in DCE mode even though it really should be in DTE
mode, hey ho). Using a little test app I've found/modified (listed below),
the CTS line can be (de)asserted whilst the device is open and the line
gets deasserted when the device closes. I have tested this port both when
acting as a console (and thus with DMA turned off) and when not used as a
console, with DMA enabled (confirmed with existing debug in driver).
This matches the behaviour of a FTDI based debug board that I've also
tried (in this case I looked at the RTS line as the device is running as a
DTE).
On my PC the same test app sets the RTS line (the serial port running as a
DTE, 8250_pnp driver) results in the CTS line being set appropriately as
well. It also stays in that state even after the serial device is closed,
this does seem right either but there you go.
With regards to the operation of the CTS/RTS line when twiddling it via
the ioctl, I think the behaviour of the IMX/FTDI is the expected one. Is
that the case?
Which I guess brings us to the lines above.
When running as an RS232 port (i.e. not rs485) the driver is using the
automatic CTSC control based on a rxFIFO watermark unless the state of the
CTS line is explictly set via an ioctl call. As such, unless I'm missing
something, the rxFIFO (and thus the automatic CTS control) is independent
of whether the DMA is running or not and thus this section looks wrong or
is at the very least in the wrong place.
Have I misunderstood something?
IIRC, the timing of DMA being enabled and disabled was changed reasonably
recently did that fix the #CTS issue possibly?
Martyn
----
Test app:
#include <stdio.h>
#include <stdlib.h>
#include <termios.h>
#include <unistd.h>
#include <sys/ioctl.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <stdbool.h>
static struct termios oldterminfo;
void closeserial(int fd)
{
tcsetattr(fd, TCSANOW, &oldterminfo);
if (close(fd) < 0)
perror("closeserial()");
}
int openserial(char *devicename)
{
int fd;
struct termios attr;
if ((fd = open(devicename, O_RDWR)) == -1) {
perror("openserial(): open()");
return 0;
}
if (tcgetattr(fd, &oldterminfo) == -1) {
perror("openserial(): tcgetattr()");
return 0;
}
attr = oldterminfo;
attr.c_cflag |= CRTSCTS | CLOCAL;
attr.c_oflag = 0;
if (tcflush(fd, TCIOFLUSH) == -1) {
perror("openserial(): tcflush()");
return 0;
}
if (tcsetattr(fd, TCSANOW, &attr) == -1) {
perror("initserial(): tcsetattr()");
return 0;
}
return fd;
}
int setRTS(int fd, int level)
{
int status;
if (ioctl(fd, TIOCMGET, &status) == -1) {
perror("setRTS(): TIOCMGET");
return 0;
}
if (level)
status |= TIOCM_RTS;
else
status &= ~TIOCM_RTS;
if (ioctl(fd, TIOCMSET, &status) == -1) {
perror("setRTS(): TIOCMSET");
return 0;
}
return 1;
}
int main(int argc, char *argv[])
{
int fd;
bool loop = true;
int state = 1;
int got;
fd = openserial(argv[1]);
if (!fd) {
fprintf(stderr, "Error while initializing %s.\n", argv[1]);
return 1;
}
while(loop) {
printf("Switching RTS %s\n", state ? "on" : "off");
setRTS(fd, state);
state = (++state) % 2;
got = getchar();
if (got == 'q')
break;
}
closeserial(fd);
return 0;
}
