Re: [RFC PATCH 01/17] net: ipa: Correct ipa_status_opcode enumeration

On Thu Oct 14, 2021 at 3:58 AM IST, Alex Elder wrote:

On 9/19/21 10:07 PM, Sireesh Kodali wrote:

quoted

From: Vladimir Lypak <redacted>

The values in the enumaration were defined as bitmasks (base 2 exponents of
actual opcodes). Meanwhile, it's used not as bitmask
ipa_endpoint_status_skip and ipa_status_formet_packet functions (compared
directly with opcode from status packet). This commit converts these values
to actual hardware constansts.

Signed-off-by: Vladimir Lypak <redacted>
Signed-off-by: Sireesh Kodali <redacted>
---
  drivers/net/ipa/ipa_endpoint.c | 8 ++++----
  1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/drivers/net/ipa/ipa_endpoint.c b/drivers/net/ipa/ipa_endpoint.c
index 5528d97110d5..29227de6661f 100644
--- a/drivers/net/ipa/ipa_endpoint.c
+++ b/drivers/net/ipa/ipa_endpoint.c

@@ -41,10 +41,10 @@
  
  /** enum ipa_status_opcode - status element opcode hardware values */
  enum ipa_status_opcode {
-	IPA_STATUS_OPCODE_PACKET		= 0x01,
-	IPA_STATUS_OPCODE_DROPPED_PACKET	= 0x04,
-	IPA_STATUS_OPCODE_SUSPENDED_PACKET	= 0x08,
-	IPA_STATUS_OPCODE_PACKET_2ND_PASS	= 0x40,
+	IPA_STATUS_OPCODE_PACKET		= 0,
+	IPA_STATUS_OPCODE_DROPPED_PACKET	= 2,
+	IPA_STATUS_OPCODE_SUSPENDED_PACKET	= 3,
+	IPA_STATUS_OPCODE_PACKET_2ND_PASS	= 6,

I haven't looked at how these symbols are used (whether you
changed it at all), but I'm pretty sure this is wrong.

The downstream tends to define "soft" symbols that must
be mapped to their hardware equivalent values. So for
example you might find a function ipa_pkt_status_parse()
that translates between the hardware status structure
and the abstracted "soft" status structure. In that
function you see, for example, that hardware status
opcode 0x1 is translated to IPAHAL_PKT_STATUS_OPCODE_PACKET,
which downstream is defined to have value 0.

In many places the upstream code eliminates that layer
of indirection where possible. So enumerated constants
are assigned specific values that match what the hardware
uses.

Looking at these again, I realised this patch is indeed wrong...
The status values are different on v2 and v3+. I guess the correct
approach here would be to use an inline function and pick the correct
status opcode, like how its handled for register defintions.

Regards,
Sireesh

-Alex

quoted

  };
  
  /** enum ipa_status_exception - status element exception type */