Re: [RFC] spi-nor: fix cross die reads on Micron multi-die devices

From: Adam Somerville
Date: Wed Jan 20 2016 - 07:01:13 EST


Thanks for looking at the this.

I can rewrite so it only affects N25Q devices, I hoped a simpler
implementation would outweigh the small overhead incurred on non
affected devices.

Do you know if there are any plans for MT25* based multi-die devices
and if they would have the same issue?



On Wed, Jan 20, 2016 at 2:45 AM, Bean Huo éææ (beanhuo)
<beanhuo@xxxxxxxxxx> wrote:
> Hi, Adam
> This is true, but this only exist in Micron 65nm spi nor N25Q.
> For our 45nm spi nor MT25Q , MT25TL and MT25Q, does exist this question.
> So I think, can you differentiate between these in your patch?
>> From: Adam Somerville <adamsomerville@xxxxxxxxx>
>> So as far as I can see there is a bug in the spi-nor driver when issuing die
>> boundary crossing reads on Micron multi-die devices.
>> Micron N25Q512A, N25Q00AA and probably any other Micron multi-die
>> devices do not support a single read request that crosses a die boundary.
>> The current behaviour is that the address on the device wraps back to the
>> start of the first die, with any data returned beyond the boundary being from
>> the start of the first die.