This is a note to let you know that I've just added the patch titled
soc/fsl/qe: round brg_freq to 1kHz granularity
to the 4.9-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git%3Ba=su...
The filename of the patch is: soc-fsl-qe-round-brg_freq-to-1khz-granularity.patch and it can be found in the queue-4.9 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree, please let stable@vger.kernel.org know about it.
From foo@baz Thu Mar 22 14:40:23 CET 2018
From: Valentin Longchamp valentin.longchamp@keymile.com Date: Fri, 17 Feb 2017 11:29:45 +0100 Subject: soc/fsl/qe: round brg_freq to 1kHz granularity
From: Valentin Longchamp valentin.longchamp@keymile.com
[ Upstream commit 2ccf80b7566cc035d903dd0ac5d7ebd25c2c1060 ]
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 Signed-off-by: Sasha Levin alexander.levin@microsoft.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- drivers/soc/fsl/qe/qe.c | 13 +++++++++++++ 1 file changed, 13 insertions(+)
--- a/drivers/soc/fsl/qe/qe.c +++ b/drivers/soc/fsl/qe/qe.c @@ -163,11 +163,15 @@ 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; @@ -185,6 +189,15 @@ 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);
Patches currently in stable-queue which might be from valentin.longchamp@keymile.com are
queue-4.9/soc-fsl-qe-round-brg_freq-to-1khz-granularity.patch