[1/2] spi: imx: set spi_bus_clk for mx1, mx31 and mx35

Commit Message

Martin Kaiser Sept. 1, 2016, 8:38 p.m. UTC

Modify spi_imx_clkdiv_2() to return the resulting bus clock frequency
when the selected clock divider is applied. Set spi_imx->spi_bus_clk to
this frequency.

If spi_bus_clk is unset, spi_imx_calculate_timeout() causes a
division by 0.

[   90.356106] Division by zero in kernel.
[   90.362631] CPU: 0 PID: 130 Comm: spidev_test Not tainted 4.8.0-rc3-next-20160825+ #105
[   90.372461] Hardware name: Freescale i.MX25 (Device Tree Support)
[   90.378708] Backtrace:
[...]
[   90.409251] [<c000dda0>] (__div0) from [<c0175b3c>] (Ldiv0+0x8/0x10)
[   90.415783] [<bf007c8c>] (spi_imx_calculate_timeout [spi_imx]) from [<bf007ee8>] (spi_imx_transfer+0x220/0x278 [spi_imx])
[   90.426924] [<bf007cc8>] (spi_imx_transfer [spi_imx]) from [<c01f1560>] (spi_bitbang_transfer_one+0x60/0x8c)
[   90.436864]  r8:d3ad52c8 r7:d3ad5800 r6:d3ad5000 r5:d3ae4f40 r4:00000000
[   90.443737] [<c01f1500>] (spi_bitbang_transfer_one) from [<c01edcb0>] (spi_transfer_one_message+0x12c/0x37c)
[   90.453668]  r8:c0a530e4 r7:d3ad5178 r6:d3ad5800 r5:d3ad5000 r4:d3b13e88 r3:00000000
[   90.461633] [<c01edb84>] (spi_transfer_one_message) from [<c01ee428>] (__spi_pump_messages+0x528/0x568)

Signed-off-by: Martin Kaiser <[e-mail]>
---
 drivers/spi/spi-imx.c |   17 ++++++++++++-----
 1 file changed, 12 insertions(+), 5 deletions(-)

Comments

Mark Brown Sept. 14, 2016, 5:05 p.m. UTC | #1

On Thu, Sep 01, 2016 at 10:38:40PM +0200, Martin Kaiser wrote:
> Modify spi_imx_clkdiv_2() to return the resulting bus clock frequency
> when the selected clock divider is applied. Set spi_imx->spi_bus_clk to
> this frequency.
> 
> If spi_bus_clk is unset, spi_imx_calculate_timeout() causes a
> division by 0.
> 
> [   90.356106] Division by zero in kernel.
> [   90.362631] CPU: 0 PID: 130 Comm: spidev_test Not tainted 4.8.0-rc3-next-20160825+ #105
> [   90.372461] Hardware name: Freescale i.MX25 (Device Tree Support)
> [   90.378708] Backtrace:

Please think hard before including backtraces in upstream reports, they
are large and contain almost no useful information relative to their
size so often obscure the relevant content in your message. If part of
the backtrace is usefully illustrative then it's usually better to pull
out the relevant sections.

Patch

diff --git a/drivers/spi/spi-imx.c b/drivers/spi/spi-imx.c
index f63cb30..5cc72be 100644
--- a/drivers/spi/spi-imx.c
+++ b/drivers/spi/spi-imx.c
@@ -186,17 +186,19 @@  static unsigned int spi_imx_clkdiv_1(unsigned int fin,
 
 /* MX1, MX31, MX35, MX51 CSPI */
 static unsigned int spi_imx_clkdiv_2(unsigned int fin,
-		unsigned int fspi)
+		unsigned int fspi, unsigned int *fres)
 {
 	int i, div = 4;
 
 	for (i = 0; i < 7; i++) {
 		if (fspi * div >= fin)
-			return i;
+			goto out;
 		div <<= 1;
 	}
 
-	return 7;
+out:
+	*fres = fin / div;
+	return i;
 }
 
 static int spi_imx_bytes_per_word(const int bpw)
@@ -482,9 +484,11 @@  static int mx31_config(struct spi_device *spi, struct spi_imx_config *config)
 {
 	struct spi_imx_data *spi_imx = spi_master_get_devdata(spi->master);
 	unsigned int reg = MX31_CSPICTRL_ENABLE | MX31_CSPICTRL_MASTER;
+	unsigned int clk;
 
-	reg |= spi_imx_clkdiv_2(spi_imx->spi_clk, config->speed_hz) <<
+	reg |= spi_imx_clkdiv_2(spi_imx->spi_clk, config->speed_hz, &clk) <<
 		MX31_CSPICTRL_DR_SHIFT;
+	spi_imx->spi_bus_clk = clk;
 
 	if (is_imx35_cspi(spi_imx)) {
 		reg |= (config->bpw - 1) << MX35_CSPICTRL_BL_SHIFT;
@@ -625,9 +629,12 @@  static int mx1_config(struct spi_device *spi, struct spi_imx_config *config)
 {
 	struct spi_imx_data *spi_imx = spi_master_get_devdata(spi->master);
 	unsigned int reg = MX1_CSPICTRL_ENABLE | MX1_CSPICTRL_MASTER;
+	unsigned int clk;
 
-	reg |= spi_imx_clkdiv_2(spi_imx->spi_clk, config->speed_hz) <<
+	reg |= spi_imx_clkdiv_2(spi_imx->spi_clk, config->speed_hz, &clk) <<
 		MX1_CSPICTRL_DR_SHIFT;
+	spi_imx->spi_bus_clk = clk;
+
 	reg |= config->bpw - 1;
 
 	if (spi->mode & SPI_CPHA)