Blackfin SPI Driver: fix bug - correct usage of struct spi_transfer.cs_change (b9b2a76a) · Commits · e / devices / android_kernel_samsung_exynos5433

According to comments in linux/spi/spi.h: * All SPI transfers start with the relevant chipselect active. Normally * it stays selected until after the last transfer in a message. Drivers * can affect the chipselect signal using cs_change. * * (i) If the transfer isn't the last one in the message, this flag is * used to make the chipselect briefly go inactive in the middle of the * message. Toggling chipselect in this way may be needed to terminate * a chip command, letting a single spi_message perform all of group of * chip transactions together. * * (ii) When the transfer is the last one in the message, the chip may * stay selected until the next transfer. On multi-device SPI busses * with nothing blocking messages going to other devices, this is just * a performance hint; starting a message to another device deselects * this one. But in other cases, this can be used to ensure correctness. * Some devices need protocol transactions to be built from a series of * spi_message submissions, where the content of one message is determined * by the results of previous messages and where the whole transaction * ends when the chipselect goes intactive. Signed-off-by:

Yi Li <yi.li@analog.com> Signed-off-by:

Bryan Wu <cooloney@kernel.org> Acked-by:

David Brownell <dbrownell@users.sourceforge.net> Cc: David Brownell <david-b@pacbell.net> Signed-off-by:

Andrew Morton <akpm@linux-foundation.org> Signed-off-by:

Linus Torvalds <torvalds@linux-foundation.org>

drivers/spi/spi_bfin5xx.c

+8 −9

Original line number	Original line	Diff line number	Diff line
	@@ -540,15 +540,13 @@ static void giveback(struct driver_data *drv_data)

	msg->state = NULL;		msg->state = NULL;

	/* disable chip select signal. And not stop spi in autobuffer mode */
	if (drv_data->tx_dma != 0xFFFF) {
	cs_deactive(drv_data, chip);
	bfin_spi_disable(drv_data);
	}

	if (!drv_data->cs_change)		if (!drv_data->cs_change)
	cs_deactive(drv_data, chip);		cs_deactive(drv_data, chip);

			/* Not stop spi in autobuffer mode */
			if (drv_data->tx_dma != 0xFFFF)
			bfin_spi_disable(drv_data);

	if (msg->complete)		if (msg->complete)
	msg->complete(msg->context);		msg->complete(msg->context);
	}		}
	@@ -757,6 +755,7 @@ static void pump_transfers(unsigned long data)

	write_STAT(drv_data, BIT_STAT_CLR);		write_STAT(drv_data, BIT_STAT_CLR);
	cr = (read_CTRL(drv_data) & (~BIT_CTL_TIMOD));		cr = (read_CTRL(drv_data) & (~BIT_CTL_TIMOD));
			if (drv_data->cs_change)
	cs_active(drv_data, chip);		cs_active(drv_data, chip);

	dev_dbg(&drv_data->pdev->dev,		dev_dbg(&drv_data->pdev->dev,
	@@ -919,11 +918,11 @@ static void pump_transfers(unsigned long data)
	} else {		} else {
	/* Update total byte transfered */		/* Update total byte transfered */
	message->actual_length += drv_data->len_in_bytes;		message->actual_length += drv_data->len_in_bytes;

	/* Move to next transfer of this msg */		/* Move to next transfer of this msg */
	message->state = next_transfer(drv_data);		message->state = next_transfer(drv_data);
			if (drv_data->cs_change)
			cs_deactive(drv_data, chip);
	}		}

	/* Schedule next transfer tasklet */		/* Schedule next transfer tasklet */
	tasklet_schedule(&drv_data->pump_transfers);		tasklet_schedule(&drv_data->pump_transfers);