Re: [PATCH V23 2/3] misc: dcc: Add driver support for Data Capture and Compare unit(DCC)

From: Trilok Soni
Date: Wed May 24 2023 - 01:10:45 EST

On 5/4/2023 11:36 PM, Souradeep Chowdhury wrote:
The DCC is a DMA Engine designed to capture and store data during system
crash or software triggers. The DCC operates based on user inputs via
the debugfs interface. The user gives addresses as inputs and these
addresses are stored in the dcc sram. In case of a system crash or a
manual software trigger by the user through the debugfs interface, the
dcc captures and stores the values at these addresses. This patch
contains the driver which has all the methods pertaining to the debugfs
interface, auxiliary functions to support all the four fundamental
operations of dcc namely read, write, read/modify/write and loop. The
probe method here instantiates all the resources necessary for dcc to
operate mainly the dedicated dcc sram where it stores the values. The
DCC driver can be used for debugging purposes without going for a reboot
since it can perform software triggers as well based on user inputs.

Also update the documentation for debugfs entries which explains the
functionalities of each debugfs file that has been created for dcc.
Update the documentation to reflect new module name for dcc.

The following is the justification of using debugfs interface over the
other alternatives like sysfs/ioctls

i) As can be seen from the debugfs attribute descriptions, some of the
debugfs attribute files here contains multiple arguments which needs to
be accepted from the user. This goes against the design style of sysfs.

ii) The user input patterns have been made simple and convenient in this
case with the use of debugfs interface as user doesn't need to shuffle
between different files to execute one instruction as was the case on
using other alternatives.

Signed-off-by: Souradeep Chowdhury <quic_schowdhu@xxxxxxxxxxx>
Reviewed-by: Alex Elder <elder@xxxxxxxxxx>

Bjorn, do you have any remaining comments here? Are you going to provide your Reviewed-by here and other patches?

If there are no comments then I would like this series to be picked by the maintainer you suggest.

---Trilok Soni