[PATCH 5.17 0452/1126] mtd: rawnand: gpmi: fix controller timings setting

From: Greg Kroah-Hartman
Date: Tue Apr 05 2022 - 04:36:18 EST

From: Dario Binacchi <dario.binacchi@xxxxxxxxxxxxxxxxxxxx>

[ Upstream commit 2970bf5a32f079e1e9197411db4fe9faccb1503a ]

Set the controller registers according to the real clock rate. The
controller registers configuration (setup, hold, timeout, ... cycles)
depends on the clock rate of the GPMI. Using the real rate instead of
the ideal one, avoids that this inaccuracy (required_rate - real_rate)
affects the registers setting.

This patch has been tested on two custom boards with i.MX28 and i.MX6
- i.MX28:
required rate 100MHz, real rate 99.3MHz
- i.MX6
required rate 100MHz, real rate 99MHz

Fixes: b1206122069a ("mtd: rawnand: gpmi: use core timings instead of an empirical derivation")
Co-developed-by: Michael Trimarchi <michael@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Michael Trimarchi <michael@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Dario Binacchi <dario.binacchi@xxxxxxxxxxxxxxxxxxxx>
Tested-by: Sascha Hauer <s.hauer@xxxxxxxxxxxxxx>
Reviewed-by: Sascha Hauer <s.hauer@xxxxxxxxxxxxxx>
Signed-off-by: Miquel Raynal <miquel.raynal@xxxxxxxxxxx>
Link: https://lore.kernel.org/linux-mtd/20220118095434.35081-3-dario.binacchi@xxxxxxxxxxxxxxxxxxxx
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
drivers/mtd/nand/raw/gpmi-nand/gpmi-nand.c | 3 +++
1 file changed, 3 insertions(+)

diff --git a/drivers/mtd/nand/raw/gpmi-nand/gpmi-nand.c b/drivers/mtd/nand/raw/gpmi-nand/gpmi-nand.c
index ded4df473928..e50db25e5ddc 100644
--- a/drivers/mtd/nand/raw/gpmi-nand/gpmi-nand.c
+++ b/drivers/mtd/nand/raw/gpmi-nand/gpmi-nand.c
@@ -648,6 +648,7 @@ static void gpmi_nfc_compute_timings(struct gpmi_nand_data *this,
const struct nand_sdr_timings *sdr)
struct gpmi_nfc_hardware_timing *hw = &this->hw;
+ struct resources *r = &this->resources;
unsigned int dll_threshold_ps = this->devdata->max_chain_delay;
unsigned int period_ps, reference_period_ps;
unsigned int data_setup_cycles, data_hold_cycles, addr_setup_cycles;
@@ -671,6 +672,8 @@ static void gpmi_nfc_compute_timings(struct gpmi_nand_data *this,

+ hw->clk_rate = clk_round_rate(r->clock[0], hw->clk_rate);
/* SDR core timings are given in picoseconds */
period_ps = div_u64((u64)NSEC_PER_SEC * 1000, hw->clk_rate);