Re: mtd raw nand denali.c broken for Intel/Altera Cyclone V

[Tim Sander <tim@krieglstein.org>]

Hi Masahiro Yamada

Sorry for the large delay. I have seen the patches at 
https://lists.infradead.org/pipermail/linux-mtd/2019-December/092852.html
Seem to resolve the question about the spare_area_skip_bytes register.

I have now set the register to 2 which seems to be the right choice on an Intel  
SocFPGA. But still i am out of luck trying to boot 5.4.5-rt3 or 5.5-rc5. I get the 
following messages during bootup booting:
[    1.825590] denali-nand-dt ff900000.nand: timeout while waiting for irq 0x1000
[    1.832936] denali-nand-dt: probe of ff900000.nand failed with error -5

But the commit c19e31d0a32dd 2017-06-13 22:45:38 predates the 4.19 kernel
release (Mon Oct 22 07:37:37 2018). So it seems there is not an obvious commit
which is causing the problem. Looking at the changes it might be that the timing
calculations in the driver changed which might also lead to a similar error.

I am booting via NFS the bootloader is placed in NOR flash.  The corresponding 
nand dts entry is updated to the new format and looks like this:
                nand@ff900000 {
                        #address-cells = <0x1>;
                        #size-cells = <0x0>;
                        compatible = "altr,socfpga-denali-nand";
                        reg = <0xff900000 0x100000 0xffb80000 0x10000>;
                        reg-names = "nand_data", "denali_reg";
                        interrupts = <0x0 0x90 0x4>;
                        clocks = <0x2d 0x1e 0x2e>;
                        clock-names = "nand", "nand_x", "ecc";
                        resets = <0x6 0x24>;
                        status = "okay";
                        nand@0 {
                                reg = <0x0>;
                                #address-cells = <0x1>;
                                #size-cells = <0x1>;
                                partition@0 {
                                        label = "work";
                                        reg = <0x0 0x10000000>;
                                };
                        };
                };

The last kernel i am able to boot is 4.19.10. I have tried booting:
5.1.21, 5.2.9, 5.3-rc8, 5.4.5-rt3 and 5.5-rc5. They all failed. Unfortunately the 
range is quite large for bisecting the problem. It also occurred to me that
all the platforms with Intel Cyclone V in mainline are development boards
which boot from SD-card not exhibiting this problem on their default boot path.

Best regards
Tim

PS: Here is some snippet from an older mail i didn't sent to the list yet which
might be superseded by now:
To get into this matter i started reading the "Intel Cyclone V HPS TRM" 
Section 13-20 Preserving Bad Block Markers:
"You can configure the NAND flash controller to skip over a specified number of 
bytes when it writes the last sector in a page to the spare area. This option 
write the desired offset to the spare_area_skip_bytes register in the config 
group. For example, if the device page size is 2 KB, and the device 
area, set the spare_area_skip_bytes register to 2. When the flash controller 
writes the last sector of the page that overlaps with the spare area, it 
spare_area_skip_bytes must be an even number. For example, if the bad block 
marker is a single byte, set spare_area_skip_bytes to 2."