diff options
| -rw-r--r-- | drivers/spi/spi.c | 11 | ||||
| -rw-r--r-- | include/linux/spi/spi.h | 4 |
2 files changed, 15 insertions, 0 deletions
diff --git a/drivers/spi/spi.c b/drivers/spi/spi.c index 6fa56590bba2..d4ba723a30da 100644 --- a/drivers/spi/spi.c +++ b/drivers/spi/spi.c @@ -778,6 +778,17 @@ static void spi_set_cs(struct spi_device *spi, bool enable) { bool enable1 = enable; + /* + * Avoid calling into the driver (or doing delays) if the chip select + * isn't actually changing from the last time this was called. + */ + if ((spi->controller->last_cs_enable == enable) && + (spi->controller->last_cs_mode_high == (spi->mode & SPI_CS_HIGH))) + return; + + spi->controller->last_cs_enable = enable; + spi->controller->last_cs_mode_high = spi->mode & SPI_CS_HIGH; + if (!spi->controller->set_cs_timing) { if (enable1) spi_delay_exec(&spi->controller->cs_setup, NULL); diff --git a/include/linux/spi/spi.h b/include/linux/spi/spi.h index b4917df79637..0e67a9a3a1d3 100644 --- a/include/linux/spi/spi.h +++ b/include/linux/spi/spi.h @@ -368,6 +368,8 @@ static inline void spi_unregister_driver(struct spi_driver *sdrv) * @cur_msg_prepared: spi_prepare_message was called for the currently * in-flight message * @cur_msg_mapped: message has been mapped for DMA + * @last_cs_enable: was enable true on the last call to set_cs. + * @last_cs_mode_high: was (mode & SPI_CS_HIGH) true on the last call to set_cs. * @xfer_completion: used by core transfer_one_message() * @busy: message pump is busy * @running: message pump is running @@ -604,6 +606,8 @@ struct spi_controller { bool auto_runtime_pm; bool cur_msg_prepared; bool cur_msg_mapped; + bool last_cs_enable; + bool last_cs_mode_high; bool fallback; struct completion xfer_completion; size_t max_dma_len; |