New subject: Add support for WCH CH341A as an SPI programmer.

31 Jan 2016

      On Wed, 27 Jan 2016 03:12:11 +0200
Urja Rannikko urjaman@gmail.com wrote:
...
Hi,
Review-ish... with some only-commentary included too.
On Mon, Jan 18, 2016 at 1:28 AM, Stefan Tauner
stefan.tauner@alumni.tuwien.ac.at wrote:
...
Signed-off-by: Urja Rannikko urjaman@gmail.com
Signed-off-by: Stefan Tauner stefan.tauner@alumni.tuwien.ac.at

Makefile        |  23 ++-
 ch341a_spi.c    | 531 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 flashrom.8.tmpl |  12 +-
 flashrom.c      |  12 ++
 programmer.h    |  13 ++
 5 files changed, 588 insertions(+), 3 deletions(-)
 create mode 100644 ch341a_spi.c

                  free_idx = (free_idx + 1) % USB_IN_TRANSFERS; /* Increment (and wrap around). */

Yeah this obvious construct is something I didnt use because I'm such
an embedded guy that I'd never ever use % in performance related
code... (i think i had some if idx>=USB_IN_TRANSFERS) idx = 0
thing)... thanks for making it saner.
:)
...
I had a fancier delay implementation done (all the way upto ms scale
using the I2C commands), but since i didnt get that fully tested, this
one will do, i'll post it as an improvement later.
Please do. I don't deem it that important but since you have
investigated the whole issue in such detail it would be a waste to not
exploit this knowledge.
...
...

  unsigned int i;

  for (i = 0; i < readcnt; i++) {

          /* FIXME: does working on words instead of bytes improve speed? */

... drop the comment? i dont really care, but i think our consensus on
IRC was that a words-wide implementation would have more issues
(alignment and such) than performance.
Or make a comment with that info.
It's gone.
...
...

          *readarr++ = swap_byte(rbuf[writecnt + i]);

  }

  return 0;

+}

+static const struct spi_master spi_master_ch341a_spi = {

  .type           = SPI_CONTROLLER_CH341A_SPI,

  /* TODO: flashrom's current maximum is 256 B. Device was tested on Linux to accept atleast 16 kB. */

  .max_data_read  = 16 * 1024,

  .max_data_write = 16 * 1024,

On linux. Not on windows usb "stack" i think... set these back to 1k?
Or test for the limit (maybe something like 4k?) and change the 1000ms
timeout, since i think the big packet would timeout on windows if
nothing else failed...
As discussed, I have tested up to 128 kB on Windows (in VM) and on
Linux with a bigger timeout and it works fine. We have agreed upon 4 kB
chunks now and using VLAs (I had an intermediate version that used
bigger chunks and relied on mallocs for them).
...
With atleast the limits dropped (or tested),  this is:
Acked-by: Urja Rannikko urjaman@gmail.com
Thanks, r1921.
-- 
Kind regards/Mit freundlichen Grüßen, Stefan Tauner

Re: [flashrom] [PATCH 3/3] Add support for WCH CH341A as an SPI programmer.