FAILED: patch "[PATCH] mtd: rawnand: gpmi: Fix setting busy timeout setting" failed to apply to 4.19-stable tree

The patch below does not apply to the 4.19-stable tree.
If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <[email protected]>.

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From 06781a5026350cde699d2d10c9914a25c1524f45 Mon Sep 17 00:00:00 2001
From: Sascha Hauer <[email protected]>
Date: Tue, 14 Jun 2022 10:31:38 +0200
Subject: [PATCH] mtd: rawnand: gpmi: Fix setting busy timeout setting

The DEVICE_BUSY_TIMEOUT value is described in the Reference Manual as:

| Timeout waiting for NAND Ready/Busy or ATA IRQ. Used in WAIT_FOR_READY | mode. This value is the number of GPMI_CLK cycles multiplied by 4096.

So instead of multiplying the value in cycles with 4096, we have to divide it by that value. Use DIV_ROUND_UP to make sure we are on the safe side, especially when the calculated value in cycles is smaller than 4096 as typically the case.

This bug likely never triggered because any timeout != 0 usually will do. In my case the busy timeout in cycles was originally calculated as 2408, which multiplied with 4096 is 0x968000. The lower 16 bits were taken for the 16 bit wide register field, so the register value was 0x8000. With 2970bf5a32f0 ("mtd: rawnand: gpmi: fix controller timings setting") however the value in cycles became 2384, which multiplied with 4096 is 0x950000. The lower 16 bit are 0x0 now resulting in an intermediate timeout when reading from NAND.

index 0b68d05846e1..889e40329956 100644
@@ -890,7 +890,7 @@ static int gpmi_nfc_compute_timings(struct gpmi_nand_data *this,
 	hw->timing0 = BF_GPMI_TIMING0_ADDRESS_SETUP(addr_setup_cycles) |
 		      BF_GPMI_TIMING0_DATA_HOLD(data_hold_cycles) |
 		      BF_GPMI_TIMING0_DATA_SETUP(data_setup_cycles);
-	hw->timing1 = BF_GPMI_TIMING1_BUSY_TIMEOUT(busy_timeout_cycles * 4096);
+	hw->timing1 = BF_GPMI_TIMING1_BUSY_TIMEOUT(DIV_ROUND_UP(busy_timeout_cycles, 4096));
 
 	/*
 	 * Derive NFC ideal delay from {3}: