From 6bb477df04366e0f69dd2f49e1ae1099069326bc Mon Sep 17 00:00:00 2001 From: Yun Zhou Date: Thu, 17 Feb 2022 22:12:34 +0800 Subject: [PATCH] spi: use specific last_cs instead of last_cs_enable Commit d40f0b6f2e21 instroduced last_cs_enable to avoid setting chipselect if it's not necessary, but it also introduces a bug. The chipselect may not be set correctly on multi-device SPI busses. The reason is that we can't judge the chipselect by bool last_cs_enable, since chipselect may be modified after other devices were accessed. So we should record the specific state of chipselect in case of confusion. Signed-off-by: Yun Zhou Link: https://lore.kernel.org/r/20220217141234.72737-1-yun.zhou@windriver.com Signed-off-by: Mark Brown --- drivers/spi/spi.c | 8 ++++++-- include/linux/spi/spi.h | 5 +++-- 2 files changed, 9 insertions(+), 4 deletions(-) diff --git a/drivers/spi/spi.c b/drivers/spi/spi.c index cd4dc31..6326e59 100644 --- a/drivers/spi/spi.c +++ b/drivers/spi/spi.c @@ -926,13 +926,14 @@ static void spi_set_cs(struct spi_device *spi, bool enable, bool force) * Avoid calling into the driver (or doing delays) if the chip select * isn't actually changing from the last time this was called. */ - if (!force && (spi->controller->last_cs_enable == enable) && + if (!force && ((enable && spi->controller->last_cs == spi->chip_select) || + (!enable && spi->controller->last_cs != spi->chip_select)) && (spi->controller->last_cs_mode_high == (spi->mode & SPI_CS_HIGH))) return; trace_spi_set_cs(spi, activate); - spi->controller->last_cs_enable = enable; + spi->controller->last_cs = enable ? spi->chip_select : -1; spi->controller->last_cs_mode_high = spi->mode & SPI_CS_HIGH; if ((spi->cs_gpiod || !spi->controller->set_cs_timing) && !activate) { @@ -3016,6 +3017,9 @@ int spi_register_controller(struct spi_controller *ctlr) goto free_bus_id; } + /* setting last_cs to -1 means no chip selected */ + ctlr->last_cs = -1; + status = device_add(&ctlr->dev); if (status < 0) goto free_bus_id; diff --git a/include/linux/spi/spi.h b/include/linux/spi/spi.h index 579d71c..7d005fa 100644 --- a/include/linux/spi/spi.h +++ b/include/linux/spi/spi.h @@ -370,7 +370,8 @@ extern struct spi_device *spi_new_ancillary_device(struct spi_device *spi, u8 ch * @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: the last chip_select that is recorded by set_cs, -1 on non chip + * selected * @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 @@ -603,7 +604,7 @@ struct spi_controller { bool auto_runtime_pm; bool cur_msg_prepared; bool cur_msg_mapped; - bool last_cs_enable; + char last_cs; bool last_cs_mode_high; bool fallback; struct completion xfer_completion; -- 2.7.4