From: Sascha Hauer s.hauer@pengutronix.de
commit 0fddf9ad06fd9f439f137139861556671673e31c upstream.
06781a5026350 Fixes the calculation of the DEVICE_BUSY_TIMEOUT register value from busy_timeout_cycles. busy_timeout_cycles is calculated wrong though: It is calculated based on the maximum page read time, but the timeout is also used for page write and block erase operations which require orders of magnitude bigger timeouts.
Fix this by calculating busy_timeout_cycles from the maximum of tBERS_max and tPROG_max.
This is for now the easiest and most obvious way to fix the driver. There's room for improvements though: The NAND_OP_WAITRDY_INSTR tells us the desired timeout for the current operation, so we could program the timeout dynamically for each operation instead of setting a fixed timeout. Also we could wire up the interrupt handler to actually detect and forward timeouts occurred when waiting for the chip being ready.
As a sidenote I verified that the change in 06781a5026350 is really correct. I wired up the interrupt handler in my tree and measured the time between starting the operation and the timeout interrupt handler coming in. The time increases 41us with each step in the timeout register which corresponds to 4096 clock cycles with the 99MHz clock that I have.
Fixes: 06781a5026350 ("mtd: rawnand: gpmi: Fix setting busy timeout setting") Fixes: b1206122069aa ("mtd: rawniand: gpmi: use core timings instead of an empirical derivation") Cc: stable@vger.kernel.org Signed-off-by: Sascha Hauer s.hauer@pengutronix.de Acked-by: Han Xu han.xu@nxp.com Tested-by: Tomasz Moń tomasz.mon@camlingroup.com Signed-off-by: Richard Weinberger richard@nod.at Signed-off-by: Tim Harvey tharvey@gateworks.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- drivers/mtd/nand/raw/gpmi-nand/gpmi-nand.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-)
--- a/drivers/mtd/nand/raw/gpmi-nand/gpmi-nand.c +++ b/drivers/mtd/nand/raw/gpmi-nand/gpmi-nand.c @@ -653,8 +653,9 @@ static void gpmi_nfc_compute_timings(str unsigned int tRP_ps; bool use_half_period; int sample_delay_ps, sample_delay_factor; - u16 busy_timeout_cycles; + unsigned int busy_timeout_cycles; u8 wrn_dly_sel; + u64 busy_timeout_ps;
if (sdr->tRC_min >= 30000) { /* ONFI non-EDO modes [0-3] */ @@ -678,7 +679,8 @@ static void gpmi_nfc_compute_timings(str addr_setup_cycles = TO_CYCLES(sdr->tALS_min, period_ps); data_setup_cycles = TO_CYCLES(sdr->tDS_min, period_ps); data_hold_cycles = TO_CYCLES(sdr->tDH_min, period_ps); - busy_timeout_cycles = TO_CYCLES(sdr->tWB_max + sdr->tR_max, period_ps); + busy_timeout_ps = max(sdr->tBERS_max, sdr->tPROG_max); + busy_timeout_cycles = TO_CYCLES(busy_timeout_ps, period_ps);
hw->timing0 = BF_GPMI_TIMING0_ADDRESS_SETUP(addr_setup_cycles) | BF_GPMI_TIMING0_DATA_HOLD(data_hold_cycles) |