Re: [RFC v1 0/3] *spi-mem: adding setup and callback function

[Boris Brezillon <boris.brezillon@xxxxxxxxxxxxx>]

On Tue, 30 Jul 2019 23:18:25 +0530
Vignesh Raghavendra <vigneshr@xxxxxx> wrote:

> On 30-Jul-19 12:24 PM, Boris Brezillon wrote:
> > Trimmed the recipient list a bit and used Frieder's new address.
> > +Sergey
> > 
> > On Mon, 29 Jul 2019 23:55:05 +0300
> > Tomer Maimon <tmaimon77@xxxxxxxxx> wrote:
> >   
> >> Hi Boris,
> >>
> >> Thanks for the prompt reply,
> >>
> >>
> >>
> >> On Mon, 29 Jul 2019 at 18:29, Boris Brezillon <boris.brezillon@xxxxxxxxxxxxx>
> >> wrote:
> >>  
> >>> Hi Tomer,
> >>>
> >>> On Mon, 29 Jul 2019 17:25:01 +0300
> >>> Tomer Maimon <tmaimon77@xxxxxxxxx> wrote:
> >>>    
> >>>> Lately we have working on Flash interface unit (FIU) SPI driver that
> >>>> using spi-mem interface, Our FIU HW module support direct Flash Rd//Wr.
> >>>>
> >>>> In our SOC (32 bit dual core ARM) we have 3 FIU's that using memory    
> >>> mapping as follow:    
> >>>>
> >>>> FIU0 - have 2 chip select and each one have 128MB memory mapping (total    
> >>> 256MB memory mapping)    
> >>>> FIU1 - have 4 chip select and each one have 128MB memory mapping (total    
> >>> 512MB memory mapping)    
> >>>> FIU2 - have 4 chip select and each one have 16MB memory mapping (total    
> >>> 32MB memory mapping)    
> >>>>
> >>>> Totally 800MB memory mapping.
> >>>>
> >>>> When the FIU driver probe it don't know the size of each Flash that
> >>>> connected to the FIU, so the entire memory mapping is allocated for each    
> >>> FIU    
> >>>> according the FIU device tree memory map parameters.    
> >>>
> >>> Do you need those mappings to be active to support simple reg accesses?
> >>>    
> >>>> It means, if we enable all three FIU's the drivers will try to allocate    
> >>> totally 800MB.    
> >>>>
> >>>> In 32bit system it is problematic because the kernel have only 1GB
> >>>> of memory allocation so the vmalloc cannot take 800MB.
> >>>>
> >>>> When implementing the FIU driver in the mtd/spi-nor we allocating memory    
> >>> address only    
> >>>> for detected Flash with exact size (usually we are not using 128MB    
> >>> Flash), and in that case usually we allocating much less memory.    
> >>>>
> >>>> To solve this issue we needed to overcome two things:
> >>>>
> >>>> 1.    Get argument from the upper layer (spi-mem layer)
> >>>> 2.    Calling the get argument function after SPI_NOR_SCAN function.    
> >>> (the MTD Flash size filled in  SPI_NOR_SCAN function)
> >>>
> >>> That's clearly breaking the layering we've tried to restore with the
> >>> spi-nor/spi-mem split, and I don't see why this is needed since we now
> >>> have a way to create direct mappings dynamically (with the dirmap API).
> >>> Have you tried implementing the dirmap hooks in your driver?    
> >>
> >>
> >>  Sorry but I wasn't familiar with the direct mapping in the spi-mem, it
> >> seems it needed to implemented in the m25p80 driver as well, am I correct?  
> > 
> > There's this patch [1] floating around. IIRC, Sergey was waiting for
> > the m25p80 -> spi-nor merge to send a v5. Vignesh, any updates on that
> > one? If you don't have time to work on that, maybe Sergey could send a
> > v5.
> >   
> 
> I did send an updated series of merging m25p80 to spi-nor last week and
> have received few comments. Will respin one more version this week
> (mostly by tomorrow).

Okay, great!