(nuttx) branch master updated: mpfs/mpfs_corespi.c: Round up divider to prevent overlock of SPI

[xiaoxiang]

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xiaoxiang pushed a commit to branch master
in repository https://gitbox.apache.org/repos/asf/nuttx.git


The following commit(s) were added to refs/heads/master by this push:
     new 8494fd2097 mpfs/mpfs_corespi.c: Round up divider to prevent overlock 
of SPI
8494fd2097 is described below

commit 8494fd2097d853320812b5b151afe3713f535ffa
Author: Ville Juven <ville.ju...@unikie.com>
AuthorDate: Tue Nov 28 19:09:45 2023 +0200

    mpfs/mpfs_corespi.c: Round up divider to prevent overlock of SPI
    
    The divider should be rounded to the next full integer to ensure that
    the resulting SPI frequency is <= target frequency, i.e. the SPI is
    not overclocked.
---
 arch/risc-v/src/mpfs/mpfs_corespi.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/arch/risc-v/src/mpfs/mpfs_corespi.c 
b/arch/risc-v/src/mpfs/mpfs_corespi.c
index 65c566a6d5..f92ed0123c 100644
--- a/arch/risc-v/src/mpfs/mpfs_corespi.c
+++ b/arch/risc-v/src/mpfs/mpfs_corespi.c
@@ -543,9 +543,9 @@ static uint32_t mpfs_spi_setfrequency(struct spi_dev_s *dev,
 
   priv->frequency = frequency;
 
-  /* Formula is SPICLK = PCLK/(2*(CFG_CLK + 1)) */
+  /* Formula is SPICLK = PCLK/(2*(CFG_CLK + 1)) (result is rounded up) */
 
-  divider = ((MPFS_FPGA_PERIPHERAL_CLK / frequency) >> 1) - 1;
+  divider = (MPFS_FPGA_PERIPHERAL_CLK / frequency) >> 1;
   priv->actual = MPFS_FPGA_PERIPHERAL_CLK / ((divider + 1) << 1);
 
   DEBUGASSERT(divider < 256u);