Alternative fix proposal for #1832

[dbuchwald]

This is alternative fix for issue #1832, but this one works with multiple bootrow write operations. When possible (v0/v3/v5), it uses NVMCTRL CTRLA page erase/page write operation, and when not available (v2/v4) it performs explicit page erase operation before page write.

[stefanrueger]

Works like a charm! I wondered about the byte write, though (see below)

Here my tests:

Creating a test file for AVR64DU28

$ avrdude -c dryrun -p 64du28 -xrandom -xseed=7 -U all:r:64du28-dry-backup.hex

avrdude: AVR device initialized and ready to accept instructions
avrdude: device signature = 0x1e9622 (probably 64du28)
         reading multiple memories ...
         eeprom          | ################################################## | 100% 0.00 s 
         flash           | ################################################## | 100% 0.00 s 
         fuses           | ################################################## | 100% 0.00 s 
         lock            | ################################################## | 100% 0.00 s 
         prodsig/sigrow  | ################################################## | 100% 0.00 s 
         bootrow         | ################################################## | 100% 0.00 s 
         userrow/usersig | ################################################## | 100% 0.00 s 
         sib             | ################################################## | 100% 0.00 s 
         writing 66740 bytes to output file 64du28-dry-backup.hex

avrdude done.  Thank you.

Writing test file to AVR64DU28 (incl bootrow)

$ avrdude -c serialupdi -p 64du28 -U all:w:64du28-dry-backup.hex

avrdude: AVR device initialized and ready to accept instructions
avrdude: device signature = 0x1e9622 (probably 64du28)
avrdude: NOT erasing chip as page erase will be used for new flash/bootrow contents
avrdude: reading 66740 bytes for multiple memories from input file 64du28-dry-backup.hex
avrdude: 256 bytes eeprom in 1 section [0, 0xff]
         writing 256 bytes to eeprom ...
         writing | ################################################## | 100% 10.24 s 
         reading | ################################################## | 100% 1.06 s 
         256 bytes of eeprom verified
avrdude: 65536 bytes flash in 1 section [0, 0xffff]: 128 pages and 0 pad bytes
         writing 65536 bytes to flash ...
         writing | ################################################## | 100% 14.04 s 
         reading | ################################################## | 100% 8.97 s 
         65536 bytes of flash verified
avrdude: 16 bytes fuses in 1 section [0, 15]
         writing 16 bytes to fuses ..., 16 bytes written, 16 verified
avrdude: 4 bytes lock in 1 section [0, 3]
         writing 4 bytes to lock ..., 4 bytes written, 4 verified
avrdude: 256 bytes bootrow in 1 section [0, 0xff]: 1 page and 0 pad bytes
         writing 256 bytes to bootrow ...
         writing | ################################################## | 100% 0.08 s 
         reading | ################################################## | 100% 0.04 s 
         256 bytes of bootrow verified
avrdude: 512 bytes userrow/usersig in 1 section [0, 0x1ff]: 1 page and 0 pad bytes
         writing 512 bytes to userrow/usersig ...
         writing | ################################################## | 100% 0.20 s 
         reading | ################################################## | 100% 0.23 s 
         512 bytes of userrow/usersig verified

avrdude done.  Thank you.

Writing bootrow a second time

$ avrdude -c serialupdi -p 64du28 -U bootrow:w:'"This is a test"':m

avrdude: AVR device initialized and ready to accept instructions
avrdude: device signature = 0x1e9622 (probably 64du28)
avrdude: reading 15 bytes for bootrow from input file "This is a test"
         in 1 section [0, 14]: 1 page and 241 pad bytes
         writing 15 bytes to bootrow ...
         writing | ################################################## | 100% 0.14 s 
         reading | ################################################## | 100% 0.04 s 
         15 bytes of bootrow verified

avrdude done.  Thank you.

Reading bootrow

$ avrdude -c serialupdi -p 64du28 -U bootrow:r:-:I

avrdude: AVR device initialized and ready to accept instructions
avrdude: device signature = 0x1e9622 (probably 64du28)
         reading bootrow memory ...
         reading | ################################################## | 100% 0.04 s 
         writing 256 bytes to output file <stdout>
:200000005468697320697320612074657374002020204040402040204040404020402020AB // 00000> This is a test.   @@@ @ @@@@ @   bootrow
:200020002020402040202040204040404040402040404020404020204040202020202020C0 // 00020>   @ @  @ @@@@@@ @@@ @@  @@      
:200040002020402040402020402020404040402020202020402040402020404020402020E0 // 00040>   @ @@  @  @@@@     @ @@  @@ @  
:20006000404020404040402040404020404020402040402020404020402040402020402000 // 00060> @@ @@@@ @@@ @@ @ @@  @@ @ @@  @ 
:20008000202020204040204020204020204040204020204040404020402020404020402080 // 00080>     @@ @  @  @@ @  @@@@ @  @@ @ 
:2000A000402040202040402040202040404020404040402040202040202020202020202080 // 000a0> @ @  @@ @  @@@ @@@@ @  @        
:2000C0004040202020402040204040404040204040204020404020402040402040404020A0 // 000c0> @@   @ @ @@@@@ @@ @ @@ @ @@ @@@ 
:2000E00040202020404020404040202020204020204040202040204020626F6F74726F7774 // 000e0> @   @@ @@@    @  @@  @ @ bootrow
:00000001FF

avrdude done.  Thank you.

This has tested the paged r/w functions. Bytewise is not needed as AVRDUDE treats bootrow as paged memory.

I don't know much about UPDI, and wondered how it implements bytewise write to flash-like memories. Seeing that this PR implements bytewise access, I temporarily forced AVRDUDE to use bytewise access by setting page_size to 1:

Change to force bytewise access

diff --git a/src/avrdude.conf.in b/src/avrdude.conf.in
index 035dd141..aa186aaf 100644
--- a/src/avrdude.conf.in
+++ b/src/avrdude.conf.in
@@ -24398,9 +24398,9 @@ part parent "64dd28" # 64du28
 
     memory "bootrow"
         size               = 256;
-        page_size          = 256;
+        page_size          = 1;
         offset             = 0x1100;
-        readsize           = 256;
+        readsize           = 1;
     ;
 
     memory "userrow"

Reading bootrow still works (but slower)

$ avrdude -c serialupdi -p 64du28 -U bootrow:r:-:I

avrdude: AVR device initialized and ready to accept instructions
avrdude: device signature = 0x1e9622 (probably 64du28)
         reading bootrow memory ...
         reading | ################################################## | 100% 0.04 s 
         writing 256 bytes to output file <stdout>
:200000005468697320697320612074657374002020204040402040204040404020402020AB // 00000> This is a test.   @@@ @ @@@@ @   bootrow
:200020002020402040202040204040404040402040404020404020204040202020202020C0 // 00020>   @ @  @ @@@@@@ @@@ @@  @@      
:200040002020402040402020402020404040402020202020402040402020404020402020E0 // 00040>   @ @@  @  @@@@     @ @@  @@ @  
:20006000404020404040402040404020404020402040402020404020402040402020402000 // 00060> @@ @@@@ @@@ @@ @ @@  @@ @ @@  @ 
:20008000202020204040204020204020204040204020204040404020402020404020402080 // 00080>     @@ @  @  @@ @  @@@@ @  @@ @ 
:2000A000402040202040402040202040404020404040402040202040202020202020202080 // 000a0> @ @  @@ @  @@@ @@@@ @  @        
:2000C0004040202020402040204040404040204040204020404020402040402040404020A0 // 000c0> @@   @ @ @@@@@ @@ @ @@ @ @@ @@@ 
:2000E00040202020404020404040202020204020204040202040204020626F6F74726F7774 // 000e0> @   @@ @@@    @  @@  @ @ bootrow
:00000001FF

avrdude done.  Thank you.

... but writing fails

$ avrdude -c serialupdi -p 64du28 -U bootrow:w:'"This is a test"':m

avrdude: AVR device initialized and ready to accept instructions
avrdude: device signature = 0x1e9622 (probably 64du28)
avrdude: reading 15 bytes for bootrow from input file "This is a test"
         in 1 section [0, 14]
         writing 15 bytes to bootrow ...
         writing | -------------------------------------------------- | 0% 10.06 s 
avrdude error: wait NVM ready timed out
avrdude error: command buffer erase failed
 *** failed
avrdude error: unable to write bootrow (rc = -1)

avrdude done.  Thank you.

Here trace.txt from

$ avrdude -c serialupdi -p 64du28 -U bootrow:w:'"This is a test"':m -vvvl trace.txt

I am 100% OK with this PR because only paged access is needed for bootrow, but just (out of curiosity) wonder how bytewise write to flash works in UPDI.