From 809b1b04df898b6d182069146231a3cbf5f2d9cc Mon Sep 17 00:00:00 2001 From: Robin Gong Date: Wed, 17 Jun 2020 06:42:08 +0800 Subject: [PATCH] spi: introduce fallback to pio Add fallback to pio mode in case dma transfer failed with error status SPI_TRANS_FAIL_NO_START. If spi client driver want to enable this feature please set xfer->error in the proper place such as dmaengine_prep_slave_sg() failure detect(but no any data put into spi bus yet). Besides, add master->fallback checking in its can_dma() so that spi core could switch to pio next time. Please refer to spi-imx.c. Signed-off-by: Robin Gong Link: https://lore.kernel.org/r/1592347329-28363-2-git-send-email-yibin.gong@nxp.com Signed-off-by: Mark Brown --- drivers/spi/spi.c | 12 ++++++++++++ include/linux/spi/spi.h | 7 +++++++ 2 files changed, 19 insertions(+) diff --git a/drivers/spi/spi.c b/drivers/spi/spi.c index 8158e28..6fa5659 100644 --- a/drivers/spi/spi.c +++ b/drivers/spi/spi.c @@ -982,6 +982,8 @@ static int __spi_unmap_msg(struct spi_controller *ctlr, struct spi_message *msg) spi_unmap_buf(ctlr, tx_dev, &xfer->tx_sg, DMA_TO_DEVICE); } + ctlr->cur_msg_mapped = false; + return 0; } #else /* !CONFIG_HAS_DMA */ @@ -1234,8 +1236,17 @@ static int spi_transfer_one_message(struct spi_controller *ctlr, if (xfer->tx_buf || xfer->rx_buf) { reinit_completion(&ctlr->xfer_completion); +fallback_pio: ret = ctlr->transfer_one(ctlr, msg->spi, xfer); if (ret < 0) { + if (ctlr->cur_msg_mapped && + (xfer->error & SPI_TRANS_FAIL_NO_START)) { + __spi_unmap_msg(ctlr, msg); + ctlr->fallback = true; + xfer->error &= ~SPI_TRANS_FAIL_NO_START; + goto fallback_pio; + } + SPI_STATISTICS_INCREMENT_FIELD(statm, errors); SPI_STATISTICS_INCREMENT_FIELD(stats, @@ -1693,6 +1704,7 @@ void spi_finalize_current_message(struct spi_controller *ctlr) spin_lock_irqsave(&ctlr->queue_lock, flags); ctlr->cur_msg = NULL; ctlr->cur_msg_prepared = false; + ctlr->fallback = false; kthread_queue_work(&ctlr->kworker, &ctlr->pump_messages); spin_unlock_irqrestore(&ctlr->queue_lock, flags); diff --git a/include/linux/spi/spi.h b/include/linux/spi/spi.h index aac57b5..b4917df 100644 --- a/include/linux/spi/spi.h +++ b/include/linux/spi/spi.h @@ -447,6 +447,8 @@ static inline void spi_unregister_driver(struct spi_driver *sdrv) * If the driver does not set this, the SPI core takes the snapshot as * close to the driver hand-over as possible. * @irq_flags: Interrupt enable state during PTP system timestamping + * @fallback: fallback to pio if dma transfer return failure with + * SPI_TRANS_FAIL_NO_START. * * Each SPI controller can communicate with one or more @spi_device * children. These make a small bus, sharing MOSI, MISO and SCK signals @@ -602,6 +604,7 @@ struct spi_controller { bool auto_runtime_pm; bool cur_msg_prepared; bool cur_msg_mapped; + bool fallback; struct completion xfer_completion; size_t max_dma_len; @@ -847,6 +850,7 @@ extern void spi_res_release(struct spi_controller *ctlr, * back unset and they need the better resolution. * @timestamped_post: See above. The reason why both exist is that these * booleans are also used to keep state in the core SPI logic. + * @error: Error status logged by spi controller driver. * * SPI transfers always write the same number of bytes as they read. * Protocol drivers should always provide @rx_buf and/or @tx_buf. @@ -940,6 +944,9 @@ struct spi_transfer { bool timestamped; struct list_head transfer_list; + +#define SPI_TRANS_FAIL_NO_START BIT(0) + u16 error; }; /** -- 2.7.4