From a02cb09bb744f130348f50707d7e9ca3ba8ef7de Mon Sep 17 00:00:00 2001 From: Yen Lin Date: Mon, 16 Jun 2014 10:43:36 -0700 Subject: [PATCH] stm32: spi: read spi->dr into a dummy variable (cherry-pick back to ToT) In setup_for_transaction(), read spi->dr into a dummy variable instead of into in_msg[0]. Since in_msg[0] is an alias for a command's port number, this will prevent a command's port number from being over-written if spi transaction is terminated early while a command is still in progress. BUG=chrome-os-partner:28979 BRANCH=nyan TEST=passed factory_test.reboot2 test for >1000 cycles Signed-off-by: Yen Lin Reviewed-on: https://chromium-review.googlesource.com/204355 Reviewed-by: Yung-chieh Lo Reviewed-by: Randall Spangler (cherry picked from commit 2b043665850f7c74cd6a4a7f24d7a18b01b378ac) Change-Id: Ia412fadcd7621f45bbb096771615ce75fe445592 Oiginal-Change-Id: I308ea954d6242fce5b3a70a14660767ac88d8242 Reviewed-on: https://chromium-review.googlesource.com/206920 Reviewed-by: Randall Spangler Commit-Queue: Yung-chieh Lo Tested-by: Yung-chieh Lo --- chip/stm32/spi.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/chip/stm32/spi.c b/chip/stm32/spi.c index f47ef89b85..960c6934b6 100644 --- a/chip/stm32/spi.c +++ b/chip/stm32/spi.c @@ -234,6 +234,7 @@ static void reply(stm32_dma_chan_t *txdma, static void setup_for_transaction(void) { stm32_spi_regs_t *spi = STM32_SPI1_REGS; + volatile uint8_t dummy __attribute__((unused)); /* Not ready to receive yet */ spi->dr = EC_SPI_NOT_READY; @@ -248,7 +249,7 @@ static void setup_for_transaction(void) * Read a byte in case there is one pending; this prevents the receive * DMA from getting that byte right when we start it */ - *in_msg = spi->dr; + dummy = spi->dr; /* Start DMA */ dma_start_rx(&dma_rx_option, sizeof(in_msg), in_msg);