From: Marek Vasut marex@denx.de
[ Upstream commit 135cbd378eab336da15de9c84bbb22bf743b38a5 ]
Since 00b80ac935539 ("spi: imx: mx51-ecspi: Move some initialisation to prepare_message hook."), the MX51_ECSPI_CONFIG write no longer happens in prepare_transfer hook, but rather in prepare_message hook, however the MX51_ECSPI_CONFIG delay is still left in prepare_transfer hook and thus has no effect. This leads to low bus frequency operation problems described in 6fd8b8503a0dc ("spi: spi-imx: Fix out-of-order CS/SCLK operation at low speeds") again.
Move the MX51_ECSPI_CONFIG write delay into the prepare_message hook as well, thus reinstating the low bus frequency fix.
Fixes: 00b80ac935539 ("spi: imx: mx51-ecspi: Move some initialisation to prepare_message hook.") Signed-off-by: Marek Vasut marex@denx.de Cc: Uwe Kleine-König u.kleine-koenig@pengutronix.de Cc: Mark Brown broonie@kernel.org Link: https://lore.kernel.org/r/20210703022300.296114-1-marex@denx.de Signed-off-by: Mark Brown broonie@kernel.org Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/spi/spi-imx.c | 38 +++++++++++++++++++------------------- 1 file changed, 19 insertions(+), 19 deletions(-)
diff --git a/drivers/spi/spi-imx.c b/drivers/spi/spi-imx.c index 39dc02e366f4..4aee3db6d6df 100644 --- a/drivers/spi/spi-imx.c +++ b/drivers/spi/spi-imx.c @@ -506,7 +506,7 @@ static int mx51_ecspi_prepare_message(struct spi_imx_data *spi_imx, { struct spi_device *spi = msg->spi; u32 ctrl = MX51_ECSPI_CTRL_ENABLE; - u32 testreg; + u32 testreg, delay; u32 cfg = readl(spi_imx->base + MX51_ECSPI_CONFIG);
/* set Master or Slave mode */ @@ -567,6 +567,23 @@ static int mx51_ecspi_prepare_message(struct spi_imx_data *spi_imx,
writel(cfg, spi_imx->base + MX51_ECSPI_CONFIG);
+ /* + * Wait until the changes in the configuration register CONFIGREG + * propagate into the hardware. It takes exactly one tick of the + * SCLK clock, but we will wait two SCLK clock just to be sure. The + * effect of the delay it takes for the hardware to apply changes + * is noticable if the SCLK clock run very slow. In such a case, if + * the polarity of SCLK should be inverted, the GPIO ChipSelect might + * be asserted before the SCLK polarity changes, which would disrupt + * the SPI communication as the device on the other end would consider + * the change of SCLK polarity as a clock tick already. + */ + delay = (2 * 1000000) / spi_imx->spi_bus_clk; + if (likely(delay < 10)) /* SCLK is faster than 100 kHz */ + udelay(delay); + else /* SCLK is _very_ slow */ + usleep_range(delay, delay + 10); + return 0; }
@@ -574,7 +591,7 @@ static int mx51_ecspi_prepare_transfer(struct spi_imx_data *spi_imx, struct spi_device *spi) { u32 ctrl = readl(spi_imx->base + MX51_ECSPI_CTRL); - u32 clk, delay; + u32 clk;
/* Clear BL field and set the right value */ ctrl &= ~MX51_ECSPI_CTRL_BL_MASK; @@ -596,23 +613,6 @@ static int mx51_ecspi_prepare_transfer(struct spi_imx_data *spi_imx,
writel(ctrl, spi_imx->base + MX51_ECSPI_CTRL);
- /* - * Wait until the changes in the configuration register CONFIGREG - * propagate into the hardware. It takes exactly one tick of the - * SCLK clock, but we will wait two SCLK clock just to be sure. The - * effect of the delay it takes for the hardware to apply changes - * is noticable if the SCLK clock run very slow. In such a case, if - * the polarity of SCLK should be inverted, the GPIO ChipSelect might - * be asserted before the SCLK polarity changes, which would disrupt - * the SPI communication as the device on the other end would consider - * the change of SCLK polarity as a clock tick already. - */ - delay = (2 * 1000000) / clk; - if (likely(delay < 10)) /* SCLK is faster than 100 kHz */ - udelay(delay); - else /* SCLK is _very_ slow */ - usleep_range(delay, delay + 10); - return 0; }