--- In .com, "Breton M. Saunders" <breton.saunders@ ...> wrote:
Hey Brett,
> I am unconvinced by the stability of the sdcard driver.
Me too. We first noticed this problem because it was causing corrupted versions of shared libraries to be loaded into RAM, causing a strange program crash. We also saw other odd behavior (playsound was cutting out on some sounds and making the sounds stutter, and saying invalid format on others). When we loaded our program from the NAND instead of the SD card all was fine. Hopefully it's an easy fix, we'll see...anyway, we've seen a lot of random weird behavior with the SD card and we're hoping this problem I reported is the root cause of it. We tried to reduce it down to a simple test case so it would be easy to reproduce.
> I'm not sure about the 7350 - but on the TS7400 there is a design issue
> (or rather lack of clarity): The port_b4 gpio line doubles up as the
> dmaenable line for dma channel 0. This is undocumented - and caused a
> problem with a board I designed. The issue arises when using dma
> enabled on the driver and channel 0 is used.
>
> The driver software for the 8 bit CPLD interfaces (7250 and 7400)
> contain a busy wait loop in them to stop faulty signaling on them. Im
> not sure about the 16 bit interfaces (e.g. the 73 series) - but there
> may be an equivalent loop or a race condition in that loop in the driver.
>
> Id suggest checking that the two external DMA signaling lines aren't
> attached to any circuitry you may be using.
Thanks for the ideas...we'll definitely check on this on Monday to make sure. We've seen this problem on two TS-7390 boards, and on one of them I believe all we had hooked up externally was the two wires to the TS uart and an ethernet cable, so I dunno.
> Does anyone fancy co-operating on reverse engineering and open sourcing
> the SDcard driver?
> Is doing that legal?
Not sure on the legality of it. I think it would be easier to just take the binary blob as is and port the open source portion of the driver to newer kernel versions perhaps? It would be an interesting thing to try (either method).
Thanks for your info!
Doug