[{"id":3683410,"web_url":"http://patchwork.ozlabs.org/comment/3683410/","msgid":"","list_archive_url":null,"date":"2026-04-28T11:54:53","subject":"Re: [PATCH] hw/i3c/dw-i3c: Fix incorrect BCR/DCR extraction during\n ENTDAA","submitter":{"id":85046,"url":"http://patchwork.ozlabs.org/api/people/85046/","name":"Philippe Mathieu-Daudé","email":"philmd@linaro.org"},"content":"Hi Ashish,\n\nOn 28/4/26 12:25, Ashish Anand wrote:\n> The target_info union in dw_i3c_addr_assign_cmd() declares pid, bcr,\n> and dcr as separate union members, causing them to all alias b[0]\n> rather than their correct positions in the ENTDAA response buffer.\n> This results in dw_i3c_update_char_table() being called with BCR and\n> DCR both read from b[0] instead of b[6] and b[7] respectively,\n> corrupting the device characteristics table on every ENTDAA operation.\n> \n> Fixed this by replacing the broken members with a nested struct using\n> uint8_t fields, matching the I3C spec wire format: six bytes of PID\n> followed by BCR and DCR.\n> \n> Signed-off-by: Ashish Anand \n> ---\n> \n> The nested struct approach avoids bitfields and __attribute__((packed)),\n> both of which introduce implementation-defined behavior for this layout.\n> \n> This bug was discovered during end-to-end ENTDAA testing where BCR and\n> DCR values observed in the char table register did not match the target's\n> actual BCR and DCR values.\n> \n> A follow-up patch adding a standalone DW I3C test machine and qtest\n> coverage for ENTDAA, private transfers, and IBI is planned.\n> \n> hw/i3c/dw-i3c.c | 17 +++++++++++------\n> 1 file changed, 11 insertions(+), 6 deletions(-)\n> \n> diff --git a/hw/i3c/dw-i3c.c b/hw/i3c/dw-i3c.c\n> index d87d42be89..1c5e09ccbb 100644\n> --- a/hw/i3c/dw-i3c.c\n> +++ b/hw/i3c/dw-i3c.c\n> @@ -1507,9 +1507,11 @@ static void dw_i3c_addr_assign_cmd(DWI3C *s, DWI3CAddrAssignCmd cmd)\n> for (i = 0; i < cmd.dev_count; i++) {\n> uint8_t addr = dw_i3c_target_addr(s, cmd.dev_index + i);\n> union {\n\n uint64_t d;\n\n> - uint64_t pid:48;\n> - uint8_t bcr;\n> - uint8_t dcr;\n> + struct {\n> + uint8_t pid[6];\n> + uint8_t bcr;\n> + uint8_t dcr;\n> + };\n> uint32_t w[2];\n> uint8_t b[8];\n> } target_info;\n> @@ -1544,9 +1546,12 @@ static void dw_i3c_addr_assign_cmd(DWI3C *s, DWI3CAddrAssignCmd cmd)\n> err = DW_I3C_RESP_QUEUE_ERR_DAA_NACK;\n> break;\n> }\n> - dw_i3c_update_char_table(s, cmd.dev_index + i,\n> - target_info.pid, target_info.bcr,\n> - target_info.dcr, addr);\n> + uint64_t pid = 0;\n> + for (int j = 0; j < 6; j++) {\n> + pid |= (uint64_t)target_info.pid[j] << (j * 8);\n\nDirectly use .b[] instead of .pid[]?\n\n> + }\n\nOr (untested):\n\n dcr = target_info.b[0];\n bcr = target_info.b[1];\n pid = extract64(be64_to_cpu(target_info.d), 16, 48);\n\nor:\n pid = be64_to_cpu(target_info.d) >> 16;\n\n> + dw_i3c_update_char_table(s, cmd.dev_index + i, pid, target_info.bcr,\n> + target_info.dcr, addr);\n> \n> /* Push the PID, BCR, and DCR to the RX queue. */\n> dw_i3c_push_rx(s, target_info.w[0]);","headers":{"Return-Path":"","X-Original-To":"incoming@patchwork.ozlabs.org","Delivered-To":"patchwork-incoming@legolas.ozlabs.org","Authentication-Results":["legolas.ozlabs.org;\n\tdkim=pass (2048-bit key;\n unprotected) header.d=linaro.org header.i=@linaro.org header.a=rsa-sha256\n header.s=google header.b=wTqZFlBV;\n\tdkim-atps=neutral","legolas.ozlabs.org;\n spf=pass (sender SPF authorized) smtp.mailfrom=nongnu.org\n (client-ip=209.51.188.17; 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