Hi Andi,
Thanks for review and taking care of patch.
We have responded to dmitry to describe more about GPI operation and
tried to explain flow in general.
We shall keep updating over email for commit log.
Please help amend below tags in commit log since we are taking it over
email:
Fixes: d8703554f4de ("i2c: qcom-geni: Add support for GPI DMA")
Reviewed-by: Andi Shyti <andi.shyti@xxxxxxxxxx>
Reviewed-by: Bryan O'Donoghue <bryan.odonoghue@xxxxxxxxxx>
Tested-by: Bryan O'Donoghue <bryan.odonoghue@xxxxxxxxxx> # qrb5165-rb5
Co-developed-by: Mukesh Kumar Savaliya <quic_msavaliy@xxxxxxxxxxx>
Signed-off-by: Viken Dadhaniya <quic_vdadhani@xxxxxxxxxxx>
On 2/1/2024 7:52 PM, Andi Shyti wrote:
Hi Viken,
On Thu, Feb 01, 2024 at 03:43:23PM +0530, Viken Dadhaniya wrote:
For i2c read operation in GSI mode, we are getting timeout
due to malformed TRE basically incorrect TRE sequence
in gpi(drivers/dma/qcom/gpi.c) driver.
TRE stands for Transfer Ring Element - which is basically an element with
size of 4 words. It contains all information like slave address,
clk divider, dma address value data size etc).
Mainly we have 3 TREs(Config, GO and DMA tre).
- CONFIG TRE : consists of internal register configuration which is
required before start of the transfer.
- DMA TRE : contains DDR/Memory address, called as DMA descriptor.
- GO TRE : contains Transfer directions, slave ID, Delay flags, Length
of the transfer.
Driver calls GPI driver API to config each TRE depending on the protocol.
If we see GPI driver, for RX operation we are configuring DMA tre and
for TX operation we are configuring GO tre.
For read operation tre sequence will be as below which is not aligned
to hardware programming guide.
- CONFIG tre
- DMA tre
- GO tre
As per Qualcomm's internal Hardware Programming Guide, we should configure
TREs in below sequence for any RX only transfer.
- CONFIG tre
- GO tre
- DMA tre
In summary, for RX only transfers, we are reordering DMA and GO TREs.
Tested covering i2c read/write transfer on QCM6490 RB3 board.
Fixes: d8703554f4de ("i2c: qcom-geni: Add support for GPI DMA")
Signed-off-by: Viken Dadhaniya <quic_vdadhani@xxxxxxxxxxx>
as Dmitry has written, please, next time don't forget the tags:
Reviewed-by: Bryan O'Donoghue <bryan.odonoghue@xxxxxxxxxx>
Tested-by: Bryan O'Donoghue <bryan.odonoghue@xxxxxxxxxx> # qrb5165-rb5
You can also add mine:
Reviewed-by: Andi Shyti <andi.shyti@xxxxxxxxxx>
Please make sure to Cc Dmitry who is raising his concerns and
check on his comments.
Andi
PS just as a reminder, if Dmitry's concerns remain related only
to the commit log, I gave you the option to agree with him in the
e-mail thread without necessarily sending a v4. I can then update
the commit log before pushing.
