linux/drivers/tty/serial/sh-sci.c, branch v4.4

serial: sh-sci: Fix length of scatterlist

2015-12-13T05:42:31Z

This patch fixes an issue that the "length" of scatterlist should be set using sg_dma_len(). Otherwise, a dmaengine driver cannot work correctly if CONFIG_NEED_SG_DMA_LENGTH=y. Fixes: 7b39d90184 (serial: sh-sci: Fix NULL pointer dereference if HIGHMEM is enabled) Signed-off-by: Yoshihiro Shimoda Signed-off-by: Geert Uytterhoeven Acked-by: Simon Horman Signed-off-by: Greg Kroah-Hartman

serial: sh-sci: Add DT support to DMA setup

2015-10-04T16:36:10Z

Add support for obtaining DMA channel information from the device tree. This requires switching from the legacy sh_dmae_slave structures with hardcoded channel numbers and the corresponding filter function to: 1. dma_request_slave_channel_compat(), - On legacy platforms, dma_request_slave_channel_compat() uses the passed DMA channel numbers that originate from platform device data, - On DT-based platforms, dma_request_slave_channel_compat() will retrieve the information from DT. 2. and the generic dmaengine_slave_config() configuration method, which requires filling in DMA register ports and slave bus widths. Signed-off-by: Geert Uytterhoeven Acked-by: Laurent Pinchart Signed-off-by: Greg Kroah-Hartman

serial: sh-sci: Pause DMA engine and get DMA status again

2015-10-04T16:36:10Z

Occasionally, DMA transaction completes _after_ DMA engine is stopped. Verify if the transaction has not finished before forcing the engine to stop and push the data Signed-off-by: Muhammad Hamza Farooq Signed-off-by: Geert Uytterhoeven Signed-off-by: Greg Kroah-Hartman

serial: sh-sci: Do not terminate DMA engine when race condition occurs

2015-10-04T16:36:10Z

When DMA packet completion and timer expiry take place at the same time, do not terminate the DMA engine, leading by submission of new descriptors, as the DMA communication hasn't necessarily stopped here. Signed-off-by: Muhammad Hamza Farooq Signed-off-by: Geert Uytterhoeven Signed-off-by: Greg Kroah-Hartman

serial: sh-sci: Call dma_async_issue_pending when transaction completes

2015-10-04T16:36:10Z

dmaengine_submit() will not start the DMA operation, it merely adds it to the pending queue. If the queue is no longer running, it won't be restarted until dma_async_issue_pending() is called. Signed-off-by: Muhammad Hamza Farooq [geert: Add more description] Signed-off-by: Geert Uytterhoeven Signed-off-by: Greg Kroah-Hartman

serial: sh-sci: Redirect port interrupts to CPU _only_ when DMA stops

2015-10-04T16:36:10Z

Since the DMA engine is not stopped everytime rx_timer_fn is called, the interrupts have to be redirected back to CPU only when incomplete DMA transaction is handled Signed-off-by: Muhammad Hamza Farooq Signed-off-by: Geert Uytterhoeven Signed-off-by: Greg Kroah-Hartman

serial: sh-sci: Remove timer on shutdown of port

2015-10-04T16:36:10Z

This prevents DMA timer timeout that can trigger after the port has been closed. Signed-off-by: Aleksandar Mitev [geert: Move del_timer_sync() outside spinlock to avoid circular locking dependency between rx_timer_fn() and del_timer_sync()] Signed-off-by: Geert Uytterhoeven Signed-off-by: Greg Kroah-Hartman

serial: sh-sci: Stop calling sci_start_rx() from sci_request_dma()

2015-10-04T16:36:10Z

There's no need to call sci_start_rx() from sci_request_dma() when DMA setup fails, as sci_startup() will call sci_start_rx() anyway. Signed-off-by: Geert Uytterhoeven Signed-off-by: Greg Kroah-Hartman

serial: sh-sci: Submit RX DMA from RX interrupt on (H)SCIF

2015-10-04T16:36:10Z

For DMA receive requests, the driver is only notified by DMA completion after the whole DMA request has been transferred. If less data is received, it will stay stuck until more data arrives. The driver handles this by setting up a timer handler from the receive interrupt, after reception of the first character. Unlike SCIFA and SCIFB, SCIF and HSCIF don't issue receive interrupts on reception of individual characters if a receive DMA request is in progress, so the timer is never set up. To fix receive DMA on SCIF and HSCIF, submit the receive DMA request from the receive interrupt handler instead. In some sense this is similar to the SCIFA/SCIFB behavior, where the RDRQE (Rx Data Transfer Request Enable) bit is also set from the receive interrupt handler. Signed-off-by: Geert Uytterhoeven Signed-off-by: Greg Kroah-Hartman

serial: sh-sci: Get rid of the workqueue to handle receive DMA requests

2015-10-04T16:36:10Z

The receive DMA workqueue function work_fn_rx() handles two things: 1. Reception of a full buffer on completion of a receive DMA request, 2. Reception of a partial buffer on receive DMA time-out. The workqueue is kicked by both the receive DMA completion handler, and by a timer to handle DMA time-out. As there are always two receive DMA requests active, it's possible that the receive DMA completion handler is called a second time before the workqueue function runs. As the time-out handler re-enables the receive interrupt, an interrupt may come in before time-out has been fully handled. Move part 1 into the receive DMA completion handler, and move part 2 into the receive DMA time-out handler, to fix these race conditions. Signed-off-by: Geert Uytterhoeven Signed-off-by: Greg Kroah-Hartman