linux.git/drivers/tty/serial/imx.c, branch v5.7

tty: imx serial: Implement support for reversing TX and RX polarity

2020-03-06T12:26:26+00:00

The peripheral has support for inverting its input and/or output
signals.  This is useful if the hardware flips polarity of the
peripheral's signal, such as swapped +/- pins on an RS-422 transceiver,
or an inverting level shifter.  Add support for these control registers
via the device tree binding.

As part of this change, make the writes of the various registers more
uniform by moving the UCR3 block up near the other registers' blocks,
since the INVT bit must be set before enabling the peripheral.

Signed-off-by: George Hilliard 
Acked-by: Uwe Kleine-König 
Link: https://lore.kernel.org/r/20200226222319.18383-3-ghilliard@kopismobile.com
Signed-off-by: Greg Kroah-Hartman

tty: serial: imx: setup the correct sg entry for tx dma

2020-02-12T19:55:21+00:00

There has oops as below happen on i.MX8MP EVK platform that has
6G bytes DDR memory.

when (xmit->tail < xmit->head) && (xmit->head == 0),
it setups one sg entry with sg->length is zero:
	sg_set_buf(sgl + 1, xmit->buf, xmit->head);

if xmit->buf is allocated from >4G address space, and SDMA only
support <4G address space, then dma_map_sg() will call swiotlb_map()
to do bounce buffer copying and mapping.

But swiotlb_map() don't allow sg entry's length is zero, otherwise
report BUG_ON().

So the patch is to correct the tx DMA scatter list.

Oops:
[  287.675715] kernel BUG at kernel/dma/swiotlb.c:497!
[  287.680592] Internal error: Oops - BUG: 0 [#1] PREEMPT SMP
[  287.686075] Modules linked in:
[  287.689133] CPU: 0 PID: 0 Comm: swapper/0 Not tainted 5.4.3-00016-g3fdc4e0-dirty #10
[  287.696872] Hardware name: FSL i.MX8MP EVK (DT)
[  287.701402] pstate: 80000085 (Nzcv daIf -PAN -UAO)
[  287.706199] pc : swiotlb_tbl_map_single+0x1fc/0x310
[  287.711076] lr : swiotlb_map+0x60/0x148
[  287.714909] sp : ffff800010003c00
[  287.718221] x29: ffff800010003c00 x28: 0000000000000000
[  287.723533] x27: 0000000000000040 x26: ffff800011ae0000
[  287.728844] x25: ffff800011ae09f8 x24: 0000000000000000
[  287.734155] x23: 00000001b7af9000 x22: 0000000000000000
[  287.739465] x21: ffff000176409c10 x20: 00000000001f7ffe
[  287.744776] x19: ffff000176409c10 x18: 000000000000002e
[  287.750087] x17: 0000000000000000 x16: 0000000000000000
[  287.755397] x15: 0000000000000000 x14: 0000000000000000
[  287.760707] x13: ffff00017f334000 x12: 0000000000000001
[  287.766018] x11: 00000000001fffff x10: 0000000000000000
[  287.771328] x9 : 0000000000000003 x8 : 0000000000000000
[  287.776638] x7 : 0000000000000000 x6 : 0000000000000000
[  287.781949] x5 : 0000000000200000 x4 : 0000000000000000
[  287.787259] x3 : 0000000000000001 x2 : 00000001b7af9000
[  287.792570] x1 : 00000000fbfff000 x0 : 0000000000000000
[  287.797881] Call trace:
[  287.800328]  swiotlb_tbl_map_single+0x1fc/0x310
[  287.804859]  swiotlb_map+0x60/0x148
[  287.808347]  dma_direct_map_page+0xf0/0x130
[  287.812530]  dma_direct_map_sg+0x78/0xe0
[  287.816453]  imx_uart_dma_tx+0x134/0x2f8
[  287.820374]  imx_uart_dma_tx_callback+0xd8/0x168
[  287.824992]  vchan_complete+0x194/0x200
[  287.828828]  tasklet_action_common.isra.0+0x154/0x1a0
[  287.833879]  tasklet_action+0x24/0x30
[  287.837540]  __do_softirq+0x120/0x23c
[  287.841202]  irq_exit+0xb8/0xd8
[  287.844343]  __handle_domain_irq+0x64/0xb8
[  287.848438]  gic_handle_irq+0x5c/0x148
[  287.852185]  el1_irq+0xb8/0x180
[  287.855327]  cpuidle_enter_state+0x84/0x360
[  287.859508]  cpuidle_enter+0x34/0x48
[  287.863083]  call_cpuidle+0x18/0x38
[  287.866571]  do_idle+0x1e0/0x280
[  287.869798]  cpu_startup_entry+0x20/0x40
[  287.873721]  rest_init+0xd4/0xe0
[  287.876949]  arch_call_rest_init+0xc/0x14
[  287.880958]  start_kernel+0x420/0x44c
[  287.884622] Code: 9124c021 9417aff8 a94363f7 17ffffd5 (d4210000)
[  287.890718] ---[ end trace 5bc44c4ab6b009ce ]---
[  287.895334] Kernel panic - not syncing: Fatal exception in interrupt
[  287.901686] SMP: stopping secondary CPUs
[  288.905607] SMP: failed to stop secondary CPUs 0-1
[  288.910395] Kernel Offset: disabled
[  288.913882] CPU features: 0x0002,2000200c
[  288.917888] Memory Limit: none
[  288.920944] ---[ end Kernel panic - not syncing: Fatal exception in interrupt ]---

Reported-by: Eagle Zhou 
Tested-by: Eagle Zhou 
Signed-off-by: Fugang Duan 
Cc: stable 
Fixes: 7942f8577f2a ("serial: imx: TX DMA: clean up sg initialization")
Reviewed-by: Uwe Kleine-König 
Link: https://lore.kernel.org/r/1581401761-6378-1-git-send-email-fugang.duan@nxp.com
Signed-off-by: Greg Kroah-Hartman

serial: imx: fix a race condition in receive path

2020-01-22T09:22:31+00:00

The main irq handler function starts by first masking disabled
interrupts in the status register values to ensure to only handle
enabled interrupts. This is important as when the RX path in the
hardware is disabled reading the RX fifo results in an external abort.

This checking must be done under the port lock, otherwise the following
can happen:

     CPU1                            | CPU2
                                     |
     irq triggers as there are chars |
     in the RX fifo                  |
				     | grab port lock
     imx_uart_int finds RRDY enabled |
     and calls imx_uart_rxint which  |
     has to wait for port lock       |
                                     | disable RX (e.g. because we're
                                     | using RS485 with !RX_DURING_TX)
                                     |
                                     | release port lock
     read from RX fifo with RX       |
     disabled => exception           |

So take the port lock only once in imx_uart_int() instead of in the
functions called from there.

Reported-by: Andre Renaud 
Cc: stable@vger.kernel.org
Signed-off-by: Uwe Kleine-König 
Link: https://lore.kernel.org/r/20200121071702.20150-1-u.kleine-koenig@pengutronix.de
Signed-off-by: Greg Kroah-Hartman

tty/serial: Migrate imx to use has_sysrq

2019-12-18T14:04:49+00:00

The SUPPORT_SYSRQ ifdeffery is not nice as:
- May create misunderstanding about sizeof(struct uart_port) between
  different objects
- Prevents moving functions from serial_core.h
- Reduces readability (well, it's ifdeffery - it's hard to follow)

In order to remove SUPPORT_SYSRQ, has_sysrq variable has been added.
Initialise it in driver's probe and remove ifdeffery.

Cc: Fabio Estevam 
Cc: NXP Linux Team 
Cc: Pengutronix Kernel Team 
Cc: Sascha Hauer 
Cc: Shawn Guo 
Cc: linux-arm-kernel@lists.infradead.org
Signed-off-by: Dmitry Safonov 
Link: https://lore.kernel.org/r/20191213000657.931618-20-dima@arista.com
Signed-off-by: Greg Kroah-Hartman

tty: serial: imx: use the sg count from dma_map_sg

2019-11-13T11:01:15+00:00

The dmaengine_prep_slave_sg needs to use sg count returned
by dma_map_sg, not use sport->dma_tx_nents, because the return
value of dma_map_sg is not always same with "nents".

Fixes: b4cdc8f61beb ("serial: imx: add DMA support for imx6q")
Signed-off-by: Peng Fan 
Link: https://lore.kernel.org/r/1573108875-26530-1-git-send-email-peng.fan@nxp.com
Signed-off-by: Greg Kroah-Hartman

Merge 5.4-rc3 into tty-next

2019-10-14T05:32:24+00:00

We need the tty/serial fixes in here as well.

Signed-off-by: Greg Kroah-Hartman

tty: serial: imx: Use platform_get_irq_optional() for optional IRQs

2019-10-10T11:12:28+00:00

All i.MX SoCs except i.MX1 have ONLY one necessary IRQ, use
platform_get_irq_optional() to get second/third IRQ which are
optional to avoid below error message during probe:

[    0.726219] imx-uart 30860000.serial: IRQ index 1 not found
[    0.731329] imx-uart 30860000.serial: IRQ index 2 not found

Fixes: 7723f4c5ecdb8d83 ("driver core: platform: Add an error message to platform_get_irq*()")
Signed-off-by: Anson Huang 
Link: https://lore.kernel.org/r/1570614559-11900-1-git-send-email-Anson.Huang@nxp.com
Signed-off-by: Greg Kroah-Hartman

serial: imx: adapt rx buffer and dma periods

2019-10-04T12:46:13+00:00

Using only 4 DMA periods for UART RX is very few if we have a high
frequency of small transfers - like in our case using Bluetooth with
many small packets via UART - causing many dma transfers but in each
only filling a fraction of a single buffer. Such a case may lead to
the situation that DMA RX transfer is triggered but no free buffer is
available. When this happens dma channel ist stopped - with the patch
"dmaengine: imx-sdma: fix dma freezes" temporarily only - with the
possible consequences that:
with disabled hw flow control:
  If enough data is incoming on UART port the RX FIFO runs over and
  characters will be lost. What then happens depends on upper layer.

with enabled hw flow control:
  If enough data is incoming on UART port the RX FIFO reaches a level
  where CTS is deasserted and remote device sending the data stops.
  If it fails to stop timely the i.MX' RX FIFO may run over and data
  get lost. Otherwise it's internal TX buffer may getting filled to
  a point where it runs over and data is again lost. It depends on
  the remote device how this case is handled and if it is recoverable.

Obviously we want to avoid having no free buffers available. So we
decrease the size of the buffers and increase their number and the
total buffer size.

Signed-off-by: Philipp Puschmann 
Reviewed-by: Lucas Stach 
Link: https://lore.kernel.org/r/20190923135916.1212-1-philipp.puschmann@emlix.com
Signed-off-by: Greg Kroah-Hartman

serial: imx: use Tx ready rather than Tx empty irq

2019-09-04T10:43:55+00:00

This should help to avoid unnecessary gaps in transmission while
adding little overhead due to low default Tx threshold level (2
bytes).

Signed-off-by: Sergey Organov 
Link: https://lore.kernel.org/r/1567017475-11919-6-git-send-email-sorganov@gmail.com
Signed-off-by: Greg Kroah-Hartman

serial: imx: fix data breakage on termios change

2019-09-04T10:43:55+00:00

imx_set_termios(): avoid writing baud rate divider registers when the
values to be written are the same as current. Any writing seems to
restart transmission/receiving logic in the hardware, that leads to
data breakage even when rate doesn't in fact change. E.g., user
switches RTS/CTS handshake and suddenly gets broken bytes.

Signed-off-by: Sergey Organov 
Link: https://lore.kernel.org/r/1567017475-11919-5-git-send-email-sorganov@gmail.com
Signed-off-by: Greg Kroah-Hartman