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Subject[PATCH v2 2/2] mtd: rawnand: arasan: Fix clock rate in NV-DDR
Date
From: Olga Kitaina <okitain@gmail.com>

According to the Arasan NAND controller spec, the flash clock rate for SDR
must be <= 100 MHz, while for NV-DDR it must be the same as the rate of the
CLK line for the mode. The driver previously always set 100 MHz for NV-DDR,
which would result in incorrect behavior for NV-DDR modes 0-4.

The appropriate clock rate can be calculated from the NV-DDR timing
parameters as 1/tCK, or for rates measured in picoseconds,
10^12 / nand_nvddr_timings->tCK_min.

Signed-off-by: Olga Kitaina <okitain@gmail.com>
Signed-off-by: Amit Kumar Mahapatra <amit.kumar-mahapatra@xilinx.com>
---
drivers/mtd/nand/raw/arasan-nand-controller.c | 18 ++++++++++++++----
1 file changed, 14 insertions(+), 4 deletions(-)

diff --git a/drivers/mtd/nand/raw/arasan-nand-controller.c b/drivers/mtd/nand/raw/arasan-nand-controller.c
index 4f6da82dd2b1..0eff069d7f80 100644
--- a/drivers/mtd/nand/raw/arasan-nand-controller.c
+++ b/drivers/mtd/nand/raw/arasan-nand-controller.c
@@ -1044,10 +1044,20 @@ static int anfc_setup_interface(struct nand_chip *chip, int target,
DQS_BUFF_SEL_OUT(dqs_mode);
}

- ret = clk_set_rate(nfc->bus_clk, ANFC_XLNX_SDR_DFLT_CORE_CLK);
- if (ret) {
- dev_err(nfc->dev, "Failed to change bus clock rate\n");
- return ret;
+ if (nand_interface_is_sdr(conf)) {
+ ret = clk_set_rate(nfc->bus_clk, ANFC_XLNX_SDR_DFLT_CORE_CLK);
+ if (ret) {
+ dev_err(nfc->dev, "Failed to change bus clock rate\n");
+ return ret;
+ }
+ } else {
+ /* ONFI timings are defined in picoseconds */
+ ret = clk_set_rate(nfc->bus_clk, div_u64((u64)NSEC_PER_SEC * 1000,
+ conf->timings.nvddr.tCK_min));
+ if (ret) {
+ dev_err(nfc->dev, "Failed to change bus clock rate\n");
+ return ret;
+ }
}

/*
--
2.17.1
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