Unverified Commit e0fe7005 authored by Geert Uytterhoeven's avatar Geert Uytterhoeven Committed by Mark Brown
Browse files

spi: rspi: Use requested instead of maximum bit rate 



Currently, the RSPI driver always tries to use the maximum configured
bit rate for communicating with a slave device, even if the transfer(s)
in the current message specify a lower rate.

Use the mininum rate specified in the message instead.
Rename rspi_data.max_speed_hz accordingly.

Signed-off-by: default avatarGeert Uytterhoeven <geert+renesas@glider.be>
Link: https://lore.kernel.org/r/20200608095940.30516-3-geert+renesas@glider.be


Signed-off-by: default avatarMark Brown <broonie@kernel.org>
parent 9ec8ade8

drivers/spi/spi-rspi.c

+21 −7
Original line number Diff line number Diff line
@@ -179,7 +179,7 @@ 


struct rspi_data {

	void __iomem *addr;

	u32 max_speed_hz;

	u32 speed_hz;

	struct spi_controller *ctlr;

	struct platform_device *pdev;

	wait_queue_head_t wait;
@@ -258,8 +258,7 @@ static int rspi_set_config_register(struct rspi_data *rspi, int access_size) 
	rspi_write8(rspi, rspi->sppcr, RSPI_SPPCR);



	/* Sets transfer bit rate */

	spbr = DIV_ROUND_UP(clk_get_rate(rspi->clk),

			    2 * rspi->max_speed_hz) - 1;

	spbr = DIV_ROUND_UP(clk_get_rate(rspi->clk), 2 * rspi->speed_hz) - 1;

	rspi_write8(rspi, clamp(spbr, 0, 255), RSPI_SPBR);



	/* Disable dummy transmission, set 16-bit word access, 1 frame */
@@ -299,14 +298,14 @@ static int rspi_rz_set_config_register(struct rspi_data *rspi, int access_size) 


	clksrc = clk_get_rate(rspi->clk);

	while (div < 3) {

		if (rspi->max_speed_hz >= clksrc/4) /* 4=(CLK/2)/2 */

		if (rspi->speed_hz >= clksrc/4) /* 4=(CLK/2)/2 */

			break;

		div++;

		clksrc /= 2;

	}



	/* Sets transfer bit rate */

	spbr = DIV_ROUND_UP(clksrc, 2 * rspi->max_speed_hz) - 1;

	spbr = DIV_ROUND_UP(clksrc, 2 * rspi->speed_hz) - 1;

	rspi_write8(rspi, clamp(spbr, 0, 255), RSPI_SPBR);

	rspi->spcmd |= div << 2;
@@ -341,7 +340,7 @@ static int qspi_set_config_register(struct rspi_data *rspi, int access_size) 
	rspi_write8(rspi, rspi->sppcr, RSPI_SPPCR);



	/* Sets transfer bit rate */

	spbr = DIV_ROUND_UP(clk_get_rate(rspi->clk), 2 * rspi->max_speed_hz);

	spbr = DIV_ROUND_UP(clk_get_rate(rspi->clk), 2 * rspi->speed_hz);

	rspi_write8(rspi, clamp(spbr, 0, 255), RSPI_SPBR);



	/* Disable dummy transmission, set byte access */
@@ -949,9 +948,24 @@ static int rspi_prepare_message(struct spi_controller *ctlr, 
{

	struct rspi_data *rspi = spi_controller_get_devdata(ctlr);

	struct spi_device *spi = msg->spi;

	const struct spi_transfer *xfer;

	int ret;



	rspi->max_speed_hz = spi->max_speed_hz;

	/*

	 * As the Bit Rate Register must not be changed while the device is

	 * active, all transfers in a message must use the same bit rate.

	 * In theory, the sequencer could be enabled, and each Command Register

	 * could divide the base bit rate by a different value.

	 * However, most RSPI variants do not have Transfer Data Length

	 * Multiplier Setting Registers, so each sequence step would be limited

	 * to a single word, making this feature unsuitable for large

	 * transfers, which would gain most from it.

	 */

	rspi->speed_hz = spi->max_speed_hz;

	list_for_each_entry(xfer, &msg->transfers, transfer_list) {

		if (xfer->speed_hz < rspi->speed_hz)

			rspi->speed_hz = xfer->speed_hz;

	}



	rspi->spcmd = SPCMD_SSLKP;

	if (spi->mode & SPI_CPOL)

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