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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.
I2C driver has geni_i2c_gpi(I2C_WRITE) function which generates GO TRE and
geni_i2c_gpi(I2C_READ)generates DMA TRE. Hence to generate GO TRE before
DMA TRE, we should move geni_i2c_gpi(I2C_WRITE) before
geni_i2c_gpi(I2C_READ) inside the I2C GSI mode transfer function
i.e. geni_i2c_gpi_xfer().
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.
I2c driver calls GPI driver API to config each TRE depending on the
protocol.
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
Fixes:
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|---|---|---|
| arch | ||
| block | ||
| certs | ||
| crypto | ||
| Documentation | ||
| drivers | ||
| fs | ||
| include | ||
| init | ||
| io_uring | ||
| ipc | ||
| kernel | ||
| lib | ||
| LICENSES | ||
| mm | ||
| net | ||
| rust | ||
| samples | ||
| scripts | ||
| security | ||
| sound | ||
| tools | ||
| usr | ||
| virt | ||
| .clang-format | ||
| .cocciconfig | ||
| .editorconfig | ||
| .get_maintainer.ignore | ||
| .gitattributes | ||
| .gitignore | ||
| .mailmap | ||
| .rustfmt.toml | ||
| COPYING | ||
| CREDITS | ||
| Kbuild | ||
| Kconfig | ||
| MAINTAINERS | ||
| Makefile | ||
| README | ||
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.