diff options
| author | Valentin Longchamp <valentin.longchamp@keymile.com> | 2017-02-17 11:29:45 +0100 |
|---|---|---|
| committer | Scott Wood <oss@buserror.net> | 2017-04-30 01:31:51 -0500 |
| commit | 2ccf80b7566cc035d903dd0ac5d7ebd25c2c1060 (patch) | |
| tree | d6e142b7618268be43935a39e1168ab8fa2e1f28 /drivers/soc | |
| parent | b54ea82f01282253c85eb7e2fd2b6c96f7a027d8 (diff) | |
| download | talos-obmc-linux-2ccf80b7566cc035d903dd0ac5d7ebd25c2c1060.tar.gz talos-obmc-linux-2ccf80b7566cc035d903dd0ac5d7ebd25c2c1060.zip | |
soc/fsl/qe: round brg_freq to 1kHz granularity
Because of integer computation rounding in u-boot (that sets the QE
brg-frequency DTS prop), the clk value is 99999999 Hz even though it is
100 MHz.
When setting brg clks that are exact divisors of 100 MHz, this small
differnce plays a role and can result in lower clks to be output (for
instance 20 MHz - divide by 5 - results in 16.666 MHz - divide by 6).
This patch fixes that by "forcing" the brg_clk to the nearest kHz when
the difference is below 2 integer rounding errors (i.e. 4).
Signed-off-by: Valentin Longchamp <valentin.longchamp@keymile.com>
Signed-off-by: Scott Wood <oss@buserror.net>
Diffstat (limited to 'drivers/soc')
| -rw-r--r-- | drivers/soc/fsl/qe/qe.c | 13 |
1 files changed, 13 insertions, 0 deletions
diff --git a/drivers/soc/fsl/qe/qe.c b/drivers/soc/fsl/qe/qe.c index d9c04f588f7f..31a094573a9d 100644 --- a/drivers/soc/fsl/qe/qe.c +++ b/drivers/soc/fsl/qe/qe.c @@ -161,11 +161,15 @@ EXPORT_SYMBOL(qe_issue_cmd); */ static unsigned int brg_clk = 0; +#define CLK_GRAN (1000) +#define CLK_GRAN_LIMIT (5) + unsigned int qe_get_brg_clk(void) { struct device_node *qe; int size; const u32 *prop; + unsigned int mod; if (brg_clk) return brg_clk; @@ -183,6 +187,15 @@ unsigned int qe_get_brg_clk(void) of_node_put(qe); + /* round this if near to a multiple of CLK_GRAN */ + mod = brg_clk % CLK_GRAN; + if (mod) { + if (mod < CLK_GRAN_LIMIT) + brg_clk -= mod; + else if (mod > (CLK_GRAN - CLK_GRAN_LIMIT)) + brg_clk += CLK_GRAN - mod; + } + return brg_clk; } EXPORT_SYMBOL(qe_get_brg_clk); |
