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spi: dw: Clamp the minimum clock speed

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The DW SPI interface has a 16-bit clock divider, where the bottom bit
of the divisor must be 0. Limit how low the clock speed can go to
prevent the clock divider from being truncated, as that could lead to
a much higher clock rate than requested.

Signed-off-by: Phil Elwell <phil@raspberrypi.com>
This commit is contained in:
Phil Elwell
2024-07-31 10:55:19 +01:00
committed by Dom Cobley
parent d0b9f2cf38
commit ec4fce8c7d
1 changed files with 1 additions and 1 deletions
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2
drivers/spi/spi-dw-core.c
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@@ -399,7 +399,7 @@ void dw_spi_update_config(struct dw_spi *dws, struct spi_device *spi,
dw_writel(dws, DW_SPI_CTRLR1, cfg->ndf ? cfg->ndf - 1 : 0); dw_writel(dws, DW_SPI_CTRLR1, cfg->ndf ? cfg->ndf - 1 : 0);
/* Note DW APB SSI clock divider doesn't support odd numbers */ /* Note DW APB SSI clock divider doesn't support odd numbers */
clk_div = (DIV_ROUND_UP(dws->max_freq, cfg->freq) + 1) & 0xfffe; clk_div = min(DIV_ROUND_UP(dws->max_freq, cfg->freq) + 1, 0xfffe) & 0xfffe;
speed_hz = dws->max_freq / clk_div; speed_hz = dws->max_freq / clk_div;
if (dws->current_freq != speed_hz) { if (dws->current_freq != speed_hz) {