linux.git/drivers/tty/serial/sh-sci.c, branch v5.1-rc5

serial: sh-sci: Fix setting SCSCR_TIE while transferring data

2019-03-19T14:37:44+00:00

We disable transmission interrupt (clear SCSCR_TIE) after all data has been transmitted
(if uart_circ_empty(xmit)). While transmitting, if the data is still in the tty buffer,
re-enable the SCSCR_TIE bit, which was done at sci_start_tx().
This is unnecessary processing, wasting CPU operation if the data transmission length is large.
And further, transmit end, FIFO empty bits disabling have also been performed in the step above.

Signed-off-by: Hoan Nguyen An 
Cc: stable 
Signed-off-by: Greg Kroah-Hartman

Merge 5.0-rc6 into tty-next

2019-02-11T08:26:45+00:00

We need the tty fixes in here for other patches to be based on.

Signed-off-by: Greg Kroah-Hartman

serial: sh-sci: Do not free irqs that have already been freed

2019-01-30T08:35:46+00:00

Since IRQs might be muxed on some parts, we need to pay attention when we
are freeing them.
Otherwise we get the ugly WARNING "Trying to free already-free IRQ 20".

Fixes: 628c534ae735 ("serial: sh-sci: Improve support for separate TEI and DRI interrupts")
Cc: stable 
Signed-off-by: Chris Brandt 
Signed-off-by: Greg Kroah-Hartman

serial: sh-sci: Make RX/TX DMA function names consistent

2019-01-08T15:56:52+00:00

Most RX/TX-specific DMA functions are prefixed with "sci_dma_[rt]x_".
Rename the exceptions to increase consistency.

Signed-off-by: Geert Uytterhoeven 
Reviewed-by: Simon Horman 
Signed-off-by: Greg Kroah-Hartman

serial: sh-sci: Fix fallback to PIO in sci_dma_rx_complete()

2019-01-08T15:56:52+00:00

When submitting a DMA request fails in sci_dma_rx_complete(), the driver
tries to fall back to PIO, but that does not work: no more data will be
received, or the kernel will even crash.

Fix this similar as in (but not identical to) sci_submit_rx():
  - On SCIF, PIO cannot take over if any DMA transactions are pending,
    hence they must be terminated first.
  - All active cookies must be invalidated, else rx_timer_fn() may
    trigger a NULL pointer dereference.
  - Restarting the port is not needed, as it is already running, but
    serial port interrupts must be directed back from the DMA engine to
    the CPU.

Signed-off-by: Geert Uytterhoeven 
Reviewed-by: Simon Horman 
Signed-off-by: Greg Kroah-Hartman

serial: sh-sci: Extract sci_dma_rx_reenable_irq()

2019-01-08T15:56:52+00:00

Extract the functionality to direct new serial port interrupts back to
the CPU into its own helper, to prepare for using it from a second
callsite.

Signed-off-by: Geert Uytterhoeven 
Reviewed-by: Simon Horman 
Signed-off-by: Greg Kroah-Hartman

serial: sh-sci: Extract sci_dma_rx_chan_invalidate()

2019-01-08T15:56:52+00:00

The cookies and channel pointer for the DMA receive channel are
invalidated in two places, and one more is planned.
Extract this functionality in a common helper.

Signed-off-by: Geert Uytterhoeven 
Reviewed-by: Simon Horman 
Signed-off-by: Greg Kroah-Hartman

serial: sh-sci: Resume PIO in sci_rx_interrupt() on DMA failure

2018-12-17T14:04:11+00:00

On (H)SCIF, sci_submit_rx() is called in the receive interrupt handler.
Hence if DMA submission fails, the interrupt handler should resume
handling reception using PIO, else no more data is received.

Make sci_submit_rx() return an error indicator, so the receive interrupt
handler can act appropriately.

Signed-off-by: Geert Uytterhoeven 
Reviewed-by: Simon Horman 
Acked-by: Wolfram Sang 
Signed-off-by: Greg Kroah-Hartman

serial: sh-sci: Fix crash in rx_timer_fn() on PIO fallback

2018-12-17T14:04:11+00:00

When falling back to PIO, active_rx must be set to a different value
than cookie_rx[i], else sci_dma_rx_find_active() will incorrectly find a
match, leading to a NULL pointer dereference in rx_timer_fn() later.

Use zero instead, which is the same value as after driver
initialization.

Signed-off-by: Geert Uytterhoeven 
Signed-off-by: Greg Kroah-Hartman

serial: sh-sci: Fix locking in sci_submit_rx()

2018-12-17T14:04:11+00:00

Some callers of sci_submit_rx() hold the port spinlock, others don't.
During fallback to PIO, the driver needs to obtain the port spinlock.
If the lock was already held, spinlock recursion is detected, causing a
deadlock: BUG: spinlock recursion on CPU#0.

Fix this by adding a flag parameter to sci_submit_rx() for the caller to
indicate the port spinlock is already held, so spinlock recursion can be
avoided.

Move the spin_lock_irqsave() up, so all DMA disable steps are protected,
which is safe as the recently introduced dmaengine_terminate_async() can
be called in atomic context.

Signed-off-by: Geert Uytterhoeven 
Reviewed-by: Simon Horman 
Signed-off-by: Greg Kroah-Hartman