On 17.02.2016 15:59, Sascha Hauer wrote:
On Wed, Feb 17, 2016 at 03:10:44PM +0100, Dirk Behme wrote:
On 17.02.2016 14:54, Sascha Hauer wrote:
Hi Dirk,
On Wed, Feb 17, 2016 at 02:42:33PM +0100, Dirk Behme wrote:
Hi Sascha,
On 17.02.2016 14:28, Sascha Hauer wrote:
This picks up a series sent by Anton Bondarenko last year. It
contains the remaining not yet upstreamed patches from Antons series
plus some more DMA related cleanup patches.
My mission was to hunt a bug in the DMA code path sometimes causing
an additional word in the RX FIFO which locked up the driver in the
next transfer. It turned out that this was no bug in the driver but
instead in the device tree: We used the wrong SDMA script for i.MX6.
The ECSPI cores are connected through the SPBA, so according to the
reference manual we need the shp/mcu scripts rather than the app/mcu
scripts.
Are you talking about what is known as "TKT238285 hardware issue"
https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/drivers/spi/spi-imx.c?id=a02bb401f8ae264be782ee57d98bdd99f14c8022
I am aware of this issue, but I have no idea if this is the same or
another issue. It says:
For TKT238285 hardware issue which may cause txfifo store data twice can only
be caught on i.mx6dl, we use pio mode instead of DMA mode on i.mx6dl.
What I saw here is that there was one word more than expected in the RX
FIFO. Since both RX and TX FIFO act synchronously it could be that the
additional word in the RX FIFO was caused by an additional word in the
TX FIFO as described above.
The question behind all this is if we could drop
https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/drivers/spi/spi-imx.c?id=a02bb401f8ae264be782ee57d98bdd99f14c8022
?
It seems on the i.MX6DL we (additionally) have another issue. I just
tested here on a i.MX6DL board with a NOR Flash connected. I saw the
same issue as I saw on the i.MX6Q, but on the i.MX6DL it cannot be fixed
by using the shp/mcu SDMA scripts.
To my understanding this might depend on the SDMA firmware itself, as in
http://git.freescale.com/git/cgit.cgi/imx/linux-2.6-imx.git/commit/?h=imx_3.14.38_6qp_ga&id=321beb210ffb382b8b5378cbf4467f8986efd52f
Freescale patches/changes the firmware, too.
Funny enough on the i.MX6DL the RXFIFO issue happens much more
frequently than on the i.MX6Q.
To my understanding, the TKT238285 hardware issue exists on both i.MX6Q
and i.MX6DL. Even though the commit message in
https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/drivers/spi/spi-imx.c?id=a02bb401f8ae264be782ee57d98bdd99f14c802
states it differently. Maybe due to timing issues it happens less often
on i.MX6Q and therefore wasn't in the focus there, yet.
Best regards
Dirk
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