This is a note to let you know that I've just added the patch titled
spi: omap2-mcspi: Fix hardcoded reference clock
to the 6.6-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
spi-omap2-mcspi-fix-hardcoded-reference-clock.patch
and it can be found in the queue-6.6 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit 718c83adbdc09afd93e4c5279d9bbe5b0e3bb45b
Author: Vaishnav Achath <vaishnav.a@xxxxxx>
Date: Tue Sep 26 17:08:12 2023 +0530
spi: omap2-mcspi: Fix hardcoded reference clock
[ Upstream commit 2d9f4877988f64f0f336983de65c365b6a7debfb ]
A hardcoded reference clock of 48 MHz is used to calculate the
clock divisor values, but the reference clock frequency can be
different across devices and can be configured which can cause
a mismatch between the reported frequency and actual SPI clock
frequency observed. Fix this by fetching the clock rate from
the clock provider and falling back to hardcoded reference only
if the clock is not supplied.
Fixes: 2cd7d393f461 ("arm64: dts: ti: k3-am654: Add McSPI DT nodes")
Signed-off-by: Vaishnav Achath <vaishnav.a@xxxxxx>
Reviewed-by: Dhruva Gole <d-gole@xxxxxx>
Link: https://lore.kernel.org/r/20230926113812.30692-1-vaishnav.a@xxxxxx
Signed-off-by: Mark Brown <broonie@xxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/drivers/spi/spi-omap2-mcspi.c b/drivers/spi/spi-omap2-mcspi.c
index 79888e6c54c25..ddf1c684bcc7d 100644
--- a/drivers/spi/spi-omap2-mcspi.c
+++ b/drivers/spi/spi-omap2-mcspi.c
@@ -125,10 +125,12 @@ struct omap2_mcspi {
struct omap2_mcspi_dma *dma_channels;
struct device *dev;
struct omap2_mcspi_regs ctx;
+ struct clk *ref_clk;
int fifo_depth;
bool target_aborted;
unsigned int pin_dir:1;
size_t max_xfer_len;
+ u32 ref_clk_hz;
};
struct omap2_mcspi_cs {
@@ -880,12 +882,12 @@ omap2_mcspi_txrx_pio(struct spi_device *spi, struct spi_transfer *xfer)
return count - c;
}
-static u32 omap2_mcspi_calc_divisor(u32 speed_hz)
+static u32 omap2_mcspi_calc_divisor(u32 speed_hz, u32 ref_clk_hz)
{
u32 div;
for (div = 0; div < 15; div++)
- if (speed_hz >= (OMAP2_MCSPI_MAX_FREQ >> div))
+ if (speed_hz >= (ref_clk_hz >> div))
return div;
return 15;
@@ -897,7 +899,7 @@ static int omap2_mcspi_setup_transfer(struct spi_device *spi,
{
struct omap2_mcspi_cs *cs = spi->controller_state;
struct omap2_mcspi *mcspi;
- u32 l = 0, clkd = 0, div, extclk = 0, clkg = 0;
+ u32 ref_clk_hz, l = 0, clkd = 0, div, extclk = 0, clkg = 0;
u8 word_len = spi->bits_per_word;
u32 speed_hz = spi->max_speed_hz;
@@ -911,14 +913,15 @@ static int omap2_mcspi_setup_transfer(struct spi_device *spi,
if (t && t->speed_hz)
speed_hz = t->speed_hz;
- speed_hz = min_t(u32, speed_hz, OMAP2_MCSPI_MAX_FREQ);
- if (speed_hz < (OMAP2_MCSPI_MAX_FREQ / OMAP2_MCSPI_MAX_DIVIDER)) {
- clkd = omap2_mcspi_calc_divisor(speed_hz);
- speed_hz = OMAP2_MCSPI_MAX_FREQ >> clkd;
+ ref_clk_hz = mcspi->ref_clk_hz;
+ speed_hz = min_t(u32, speed_hz, ref_clk_hz);
+ if (speed_hz < (ref_clk_hz / OMAP2_MCSPI_MAX_DIVIDER)) {
+ clkd = omap2_mcspi_calc_divisor(speed_hz, ref_clk_hz);
+ speed_hz = ref_clk_hz >> clkd;
clkg = 0;
} else {
- div = (OMAP2_MCSPI_MAX_FREQ + speed_hz - 1) / speed_hz;
- speed_hz = OMAP2_MCSPI_MAX_FREQ / div;
+ div = (ref_clk_hz + speed_hz - 1) / speed_hz;
+ speed_hz = ref_clk_hz / div;
clkd = (div - 1) & 0xf;
extclk = (div - 1) >> 4;
clkg = OMAP2_MCSPI_CHCONF_CLKG;
@@ -1448,8 +1451,6 @@ static int omap2_mcspi_probe(struct platform_device *pdev)
ctlr->cleanup = omap2_mcspi_cleanup;
ctlr->target_abort = omap2_mcspi_target_abort;
ctlr->dev.of_node = node;
- ctlr->max_speed_hz = OMAP2_MCSPI_MAX_FREQ;
- ctlr->min_speed_hz = OMAP2_MCSPI_MAX_FREQ >> 15;
ctlr->use_gpio_descriptors = true;
platform_set_drvdata(pdev, ctlr);
@@ -1519,6 +1520,14 @@ static int omap2_mcspi_probe(struct platform_device *pdev)
goto free_ctlr;
}
+ mcspi->ref_clk = devm_clk_get_optional_enabled(&pdev->dev, NULL);
+ if (mcspi->ref_clk)
+ mcspi->ref_clk_hz = clk_get_rate(mcspi->ref_clk);
+ else
+ mcspi->ref_clk_hz = OMAP2_MCSPI_MAX_FREQ;
+ ctlr->max_speed_hz = mcspi->ref_clk_hz;
+ ctlr->min_speed_hz = mcspi->ref_clk_hz >> 15;
+
pm_runtime_use_autosuspend(&pdev->dev);
pm_runtime_set_autosuspend_delay(&pdev->dev, SPI_AUTOSUSPEND_TIMEOUT);
pm_runtime_enable(&pdev->dev);
