Messages in this thread | | | Date | Wed, 22 Nov 2023 01:04:41 +0100 | From | Christian Marangi <> | Subject | Re: [net-next PATCH] net: phy: aquantia: make mailbox interface4 lsw addr mask more specific |
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On Tue, Nov 21, 2023 at 03:58:12PM -0800, Jakub Kicinski wrote: > On Wed, 22 Nov 2023 00:48:01 +0100 Christian Marangi wrote: > > > Not so sure about this one, it puts the u32 on the stack, and takes > > > the address of it: > > > > > > u32 word; > > > > > > word = (__force u32)cpu_to_be32(word); > > > crc = crc_ccitt_false(crc, (u8 *)&word, sizeof(word)); > > > > > > so the endian will matter here. My guess is that this part is correct. > > Actually I'm wrong about this, you're reading and writing the data, > so endian conversion happens twice. Canceling itself out. > > > Ehhh this is problematic. Data comes from nvmem or filesystem, in theory > > they should not be touched/converted. > > > > nvmem_cell_read or request_firmware return pointer to u8 and it's the > > firmware (that is always in LE) > > > > If data is not converted and passed AS IS from what is read to the > > allocated data, then data should be always swapped. > > (this PHY is fun... it's probably BE internally but expect LE stuff in > > the mailbox, as it does emit BE CRC.) > > > > Any idea where I can verify if nvmem_cell_read or request_firmware makes > > any kind of endianess conversion on the data it does read? > > The underlying storage should be byte-accessible, so neither interface > should change anything about the endian. > > You should probably switch get_unaligned_le32() for reading it into > the word variable, tho.
I don't need to read it, I need to pass the data directly from what is read to mailbox so using get_unaligned_le32 would actually make a conversion. Anyway thanks a lot for putting some extra words and make me check this further! Will send a v2 tomorrow!
-- Ansuel
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