[9fans] raspberry pi sdhost driver

[9fans] raspberry pi sdhost driver

[Richard Miller]

The pi3 native wifi driver (ether4330.c) recently added to
/n/sources/contrib/miller/9/bcm had an annoying limitation.
The sdio interface to the wifi chip is via the emmc host
adapter on the bcm283x SoC, which previously had been used
for the sdcard.  This meant a kernel could be configured to
use wifi or sdcard but not both.

Fortunately there is a secondary, Broadcom proprietary (and
undocumented) "sdhost" interface which can be used for the
sdcard instead.  This interface has been present on all the
pi models, but a linux driver only appeared when the pi3
was released.

I've now added a driver (sdhost.c) for this interface, which
will be used in place of emmc if you add sdhost to the "link"
section of the kernel config file.  I recommend this even if
you don't use wifi, since the sdhost hardware can squeeze a
bit more performance out of cards with "high speed" capability
(which nowadays means most of them).  You'll also need to update
io.h, and sdmmc.c to get the new code which recognises high speed
cards.

I've also updated the old emmc driver to increase its speed fairly
dramatically; but the emmc must always divide its 250Mhz input clock
by an even number, which means it can drive 50Mhz cards only up to
41.67 Mhz.  The sdhost driver doesn't have this limitation.

Re: [9fans] raspberry pi sdhost driver

[Richard Miller]

> The sdhost driver doesn't have this limitation.

Should read "the sdhost hardware doesn't have this limitation".

Re: [9fans] raspberry pi sdhost driver

[Bakul Shah]

On Sun, 11 Dec 2016 16:57:27 GMT Richard Miller <9fans@hamnavoe.com> wrote:
> The pi3 native wifi driver (ether4330.c) recently added to
> /n/sources/contrib/miller/9/bcm had an annoying limitation.

"9fs sources" seems to work but "ls /n/sources" with a clone
failed message.  Strange that 9fs sources works....

Is this a known issue or temporary? Is there an alternate
place?

Thanks.

Re: [9fans] raspberry pi sdhost driver

[Bakul Shah]

On Sat, 17 Dec 2016 20:20:22 PST Bakul Shah <bakul@bitblocks.com> wrote:
> On Sun, 11 Dec 2016 16:57:27 GMT Richard Miller <9fans@hamnavoe.com> wrote:
> > The pi3 native wifi driver (ether4330.c) recently added to
> > /n/sources/contrib/miller/9/bcm had an annoying limitation.
>
> "9fs sources" seems to work but "ls /n/sources" with a clone
> failed message.  Strange that 9fs sources works....
>
> Is this a known issue or temporary? Is there an alternate
> place?

This seems to have something to do with my local NAT gateway
machine.  Sorry for the noise.