Re: [Qemu-devel] [PATCH] [M25P80] Make sure not to overrun the internal data buffer.

["mar.krzeminski" <mar.krzeminski@gmail.com>]

W dniu 30.12.2016 o 18:14, Jean-Christophe DUBOIS pisze:
> Le 30/12/2016 à 16:39, mar.krzeminski a écrit :
>> I got some time, and reproduced the problem. Here are some logs with 
>> m25p80 debugs:
>> : decode_new_cmd: decoded new command:9f
>> : decode_new_cmd: populated jedec code
>> : decode_new_cmd: decoded new command:0
>> : decode_new_cmd: decoded new command:0 //Getting flash Id in above 4 
>> lines -> OK (but missing CS)
>> Found sst25vf016b compatible flash device
>> : decode_new_cmd: decoded new command:6 //Write enable, command 
>> without payload, so it is ok
>> : decode_new_cmd: decoded new command:1 //Write to status register, 
>> guest sends data
>> INFO: spi0.0: sst25vf016b (2048 Kbytes)
>> INFO: spi0.0: mtd
>>   .name = spi0.0,
>>   .size = 0x200000 (2MiB)
>>   .erasesize = 0x00001000 (4KiB)
>>   .numeraseregions = 0
>> Segmentation fault (core dumped) //Here probably guest try to send 
>> some data
>>
>> The root cause why m25p80 enter strange state is that CS line is not 
>> selected/deselected at all- there is missing debug from m25p80_cs.
>> In spi transfer CS line (here qemu_irq) should be 0 before begin of 
>> every message, and set after end of transmission.
>> In case of simple WREN command you should see something like this:
>> : m25p80_cs: deselect
>> : decode_new_cmd: decoded new command:6
>> : m25p80_cs: select
>>
>> Can you check spi controller model code?
>
> I'll double check.
>
> But why is the SPI memory/device even responding if CS is not set ?
Looking at ssi code it should not.
Flash (so the m25p80) is responding when CS line is low and it seem that 
this is default.

Thanks,
Marcin

>
>>
>> Thanks,
>> Marcin
>>
>>
>
>