Kalle Valo <kvalo@xxxxxxxxxxxxxx> writes: > Martin Blumenstingl <martin.blumenstingl@xxxxxxxxxxxxxx> writes: > >> There are two types of swapping the EEPROM data in the ath9k driver. >> Before this series one type of swapping could not be used without the >> other. >> >> The first type of swapping looks at the "magic bytes" at the start of >> the EEPROM data and performs swab16 on the EEPROM contents if needed. >> The second type of swapping is EEPROM format specific and swaps >> specific fields within the EEPROM itself (swab16, swab32 - depends on >> the EEPROM format). >> >> With this series the second part now looks at the EEPMISC register >> inside the EEPROM, which uses a bit to indicate if the EEPROM data >> is Big Endian (this is also done by the FreeBSD kernel). >> This has a nice advantage: currently there are some out-of-tree hacks >> (in OpenWrt and LEDE) where the EEPROM has a Big Endian header on a >> Big Endian system (= no swab16 is performed) but the EEPROM itself >> indicates that it's data is Little Endian. Until now the out-of-tree >> code simply did a swab16 before passing the data to ath9k, so ath9k >> first did the swab16 - this also enabled the format specific swapping. >> These out-of-tree hacks are still working with the new logic, but it >> is recommended to remove them. This implementation is based on a >> discussion with Arnd Bergmann who raised concerns about the >> robustness and portability of the swapping logic in the original OF >> support patch review, see [0]. >> >> After a second round of patches (= v1 of this series) neither Arnd >> Bergmann nor I were really happy with the complexity of the EEPROM >> swapping logic. Based on a discussion (see [1] and [2]) we decided >> that ath9k should use a defined format (specifying the endianness >> of the data - I went with __le16 and __le32) when accessing the >> EEPROM fields. A benefit of this is that we enable the EEPMISC based >> swapping logic by default, just like the FreeBSD driver, see [3]. On >> the devices which I have tested (see below) ath9k now works without >> having to specify the "endian_check" field in ath9k_platform_data (or >> a similar logic which could provide this via devicetree) as ath9k now >> detects the endianness automatically. Only EEPROMs which are mangled >> by some out-of-tree code still need the endian_check flag (or one can >> simply remove that mangling from the out-of-tree code). >> >> Testing: >> - tested by myself on AR9287 with Big Endian EEPROM >> - tested by myself on AR9227 with Little Endian EEPROM >> - tested by myself on AR9381 (using the ar9003_eeprom implementation, >> which did not suffer from this whole problem) >> - how do we proceed with testing? maybe we could keep this in a >> feature-branch and add these patches to LEDE once we have an ACK to >> get more people to test this >> >> This series depends on my other series (v7): >> "add devicetree support to ath9k" - see [4] > > I think this looks pretty good. If there's a bug somewhere it should be > quite easy to fix so I'm not that worried and would be willing to take > these as soon as I have applied the dependency series. IIRC your > devicetree patches will have at least one more review round so that will > take some time still. In the meantime it would be great if LEDE folks > could take a look at these and comment (or test). So are everyone happy with this? I haven't seen any comments. If I don't here anything I'm planning to take these, most likely for 4.11. -- Kalle Valo
