Re: [PATCH v1 1/4] mhi_bus: core: Add support for MHI host interface

From: Sujeev Dias
Date: Sat Apr 28 2018 - 10:28:28 EST

Thanks for quick feedback

On 04/27/2018 12:22 AM, Greg Kroah-Hartman wrote:
On Thu, Apr 26, 2018 at 07:23:28PM -0700, Sujeev Dias wrote:
MHI Host Interface is a communication protocol to be used by the host
to control and communcate with modem over a high speed peripheral bus.
This module will allow host to communicate with external devices that
support MHI protocol.

Signed-off-by: Sujeev Dias <sdias@xxxxxxxxxxxxxx>
No one else has ever reviewed this code before? That's not good, please
at the very least, have someone else at your company go over it first.
I don't want to be the ones having to point out all of the "obvious"
issues :)

This code has gone thru rigorous code review and testing, before I submit next patch
I will have multiple people sign off on it.
Documentation/00-INDEX | 2 +
Documentation/devicetree/bindings/bus/mhi.txt | 141 +++
Documentation/mhi.txt | 235 ++++
drivers/bus/Kconfig | 17 +
drivers/bus/Makefile | 1 +
drivers/bus/mhi/Makefile | 8 +
drivers/bus/mhi/core/Makefile | 1 +
drivers/bus/mhi/core/mhi_boot.c | 593 ++++++++++
drivers/bus/mhi/core/mhi_dtr.c | 177 +++
drivers/bus/mhi/core/mhi_init.c | 1290 +++++++++++++++++++++
drivers/bus/mhi/core/mhi_internal.h | 732 ++++++++++++
drivers/bus/mhi/core/mhi_main.c | 1476 +++++++++++++++++++++++++
drivers/bus/mhi/core/mhi_pm.c | 1177 ++++++++++++++++++++
include/linux/mhi.h | 694 ++++++++++++
include/linux/mod_devicetable.h | 11 +
15 files changed, 6555 insertions(+)
And a 6555 line patch is a bit hard to consume all at once. Can't this
be split up into much more reviewable chunks? Look at how some of the
other new bus subsystems got added to the tree recently. They were
submitted in longer patch series, but smaller sized patches
individually. That makes things much easier to review.

For example, there is no reason your debugfs stuff needs to be in this
initial patch. That should be in a separate one, right? Same for
firmware download. Please take the time to break this up into logical

Like my son's math teacher keeps telling him, "show your work, not just
an answer at the bottom of the page".

Also, it is required by the DT maintainers to split that file alone up
into a separate patch to be even considered for merging.

One thing I can tell you right now that isn't acceptable:
That is interesting because internally it's separated, and I squash them thinking
it was preferred. I will separate them out to functional blocks
Don't have a separate config option for debugging. No one will enable
it, which makes it pointless. Everything has to be dynamic these days.
Intention was to completely compile out MHI_VERB messages because we have those messages in
data path. For release build, we wanted to reduce as much mips as possible. However, for
debugging these messages are extremely helpful.

I will look into tracepoints...
+#define MHI_VERB(fmt, ...) do { \
+ if (mhi_cntrl->klog_lvl <= MHI_MSG_LVL_VERBOSE) \
+ pr_debug("[D][%s] " fmt, __func__, ##__VA_ARGS__);\
+} while (0)
+#define MHI_VERB(fmt, ...)
+#define MHI_LOG(fmt, ...) do { \
+ if (mhi_cntrl->klog_lvl <= MHI_MSG_LVL_INFO) \
+ pr_info("[I][%s] " fmt, __func__, ##__VA_ARGS__);\
+} while (0)
+#define MHI_ERR(fmt, ...) do { \
+ if (mhi_cntrl->klog_lvl <= MHI_MSG_LVL_ERROR) \
+ pr_err("[E][%s] " fmt, __func__, ##__VA_ARGS__); \
+} while (0)
+#define MHI_CRITICAL(fmt, ...) do { \
+ if (mhi_cntrl->klog_lvl <= MHI_MSG_LVL_CRITICAL) \
+ pr_alert("[C][%s] " fmt, __func__, ##__VA_ARGS__); \
+} while (0)
And do not roll your own debugging/logging macros. Use what is given to
you (dev_info(), dev_err(), dev_dbg()), they are there for a reason. By
going around them, you circumvent the whole of the kernel logging
infrastructure and declare that your tiny bus is somehow more "special"
than it.

And I doubt you want to make such a statement :)

well :).. I will remove them in next revision.

greg k-h
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