From: Subash Abhinov Kasiviswanathan <subashab@codeaurora.org>
To: Alex Elder <elder@linaro.org>
Cc: arnd@arndb.de, david.brown@linaro.org, agross@kernel.org,
davem@davemloft.net, bjorn.andersson@linaro.org,
ilias.apalodimas@linaro.org, cpratapa@codeaurora.org,
syadagir@codeaurora.org, evgreen@chromium.org,
benchan@google.com, ejcaruso@google.com, netdev@vger.kernel.org,
linux-arm-msm@vger.kernel.org,
linux-arm-kernel@lists.infradead.org,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH 1/8] net: qualcomm: rmnet: fix struct rmnet_map_header
Date: Mon, 20 May 2019 19:32:29 -0600 [thread overview]
Message-ID: <d90f8ccdc1f76f9166f269eb71a14f7f@codeaurora.org> (raw)
In-Reply-To: <81fd1e01-b8e3-f86a-fcc9-2bcbc51bd679@linaro.org>
>> If the above illustration is supposed to be in network byte order,
>> then it is wrong. The documentation has the definition for the MAP
>> packet.
>
> Network *bit* order is irrelevant to the host. Host memory is
> byte addressable only, and bit 0 is the low-order bit.
>
>> Packet format -
>>
>> Bit 0 1 2-7 8 - 15 16
>> - 31
>> Function Command / Data Reserved Pad Multiplexer ID
>> Payload length
>> Bit 32 - x
>> Function Raw Bytes
>
> I don't know how to interpret this. Are you saying that the low-
> order bit of the first byte is the command/data flag? Or is it
> the high-order bit of the first byte?
>
> I'm saying that what I observed when building the code was that
> as originally defined, the cd_bit field was the high-order bit
> (bit 7) of the first byte, which I understand to be wrong.
>
> If you are telling me that the command/data flag resides at bit
> 7 of the first byte, I will update the field masks in a later
> patch in this series to reflect that.
>
Higher order bit is Command / Data.
>> The driver was written assuming that the host was running ARM64, so
>> the structs are little endian. (I should have made it compatible
>> with big and little endian earlier so that is my fault).
>
> Little endian and big endian have no bearing on the host's
> interpretation of bits within a byte.
>
> Please clarify. I want the patches to be correct, and what
> you're explaining doesn't really straighten things out for me.
>
> -Alex
Can't this bitfields just be used similar to how struct tcphdr &
iphdr are currently defined. That way, you dont have to make
these many changes.
diff --git a/drivers/net/ethernet/qualcomm/rmnet/rmnet_map.h
b/drivers/net/ethernet/qualcomm/rmnet/rmnet_map.h
index 884f1f5..302d1db 100644
--- a/drivers/net/ethernet/qualcomm/rmnet/rmnet_map.h
+++ b/drivers/net/ethernet/qualcomm/rmnet/rmnet_map.h
@@ -40,9 +40,17 @@ enum rmnet_map_commands {
};
struct rmnet_map_header {
+#if defined(__LITTLE_ENDIAN_BITFIELD)
u8 pad_len:6;
u8 reserved_bit:1;
u8 cd_bit:1;
+#elif defined (__BIG_ENDIAN_BITFIELD)
+ u8 cd_bit:1;
+ u8 reserved_bit:1;
+ u8 pad_len:6;
+#else
+#error "Please fix <asm/byteorder.h>"
+#endif
u8 mux_id;
__be16 pkt_len;
} __aligned(1);
--
Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum,
a Linux Foundation Collaborative Project
next prev parent reply other threads:[~2019-05-21 1:32 UTC|newest]
Thread overview: 24+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-05-20 13:53 [PATCH 0/8] net: introduce "include/linux/if_rmnet.h" Alex Elder
2019-05-20 13:53 ` [PATCH 1/8] net: qualcomm: rmnet: fix struct rmnet_map_header Alex Elder
2019-05-20 15:38 ` Bjorn Andersson
2019-05-20 20:11 ` Subash Abhinov Kasiviswanathan
2019-05-20 21:23 ` Alex Elder
2019-05-21 1:32 ` Subash Abhinov Kasiviswanathan [this message]
2019-05-21 2:30 ` Alex Elder
2019-05-21 3:07 ` Bjorn Andersson
2019-05-21 11:03 ` Alex Elder
2019-05-20 13:53 ` [PATCH 2/8] net: qualcomm: rmnet: kill RMNET_MAP_GET_*() accessor macros Alex Elder
2019-05-20 15:41 ` Bjorn Andersson
2019-05-20 13:53 ` [PATCH 3/8] net: qualcomm: rmnet: use field masks instead of C bit-fields Alex Elder
2019-05-20 15:43 ` Bjorn Andersson
2019-05-20 13:53 ` [PATCH 4/8] net: qualcomm: rmnet: don't use C bit-fields in rmnet checksum header Alex Elder
2019-05-20 15:49 ` Bjorn Andersson
2019-05-20 13:53 ` [PATCH 5/8] net: qualcomm: rmnet: don't use C bit-fields in rmnet checksum trailer Alex Elder
2019-05-20 17:17 ` Bjorn Andersson
2019-05-20 13:53 ` [PATCH 6/8] net: qualcomm: rmnet: get rid of a variable in rmnet_map_ipv4_ul_csum_header() Alex Elder
2019-05-20 17:17 ` Bjorn Andersson
2019-05-20 13:53 ` [PATCH 7/8] net: qualcomm: rmnet: mark endianness of struct rmnet_map_dl_csum_trailer fields Alex Elder
2019-05-20 17:17 ` Bjorn Andersson
2019-05-20 13:53 ` [PATCH 8/8] net: introduce "include/linux/if_rmnet.h" Alex Elder
2019-05-20 17:18 ` Bjorn Andersson
2019-05-20 18:00 ` [PATCH 0/8] " Alex Elder
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