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SubjectRe: [PATCH] ath9k: Check for errors when reading SREV register
Date
Tim Schumacher <timschumi@gmx.de> writes:

> Right now, if an error is encountered during the SREV register
> read (i.e. an EIO in ath9k_regread()), that error code gets
> passed all the way to __ath9k_hw_init(), where it is visible
> during the "Chip rev not supported" message.
>
> ath9k_htc 1-1.4:1.0: ath9k_htc: HTC initialized with 33 credits
> ath: phy2: Mac Chip Rev 0x0f.3 is not supported by this driver
> ath: phy2: Unable to initialize hardware; initialization status: -95
> ath: phy2: Unable to initialize hardware; initialization status: -95
> ath9k_htc: Failed to initialize the device
>
> Check for -EIO explicitly in ath9k_hw_read_revisions() and return
> a boolean based on the success of the operation. Check for that in
> __ath9k_hw_init() and abort with a more debugging-friendly message
> if reading the revisions wasn't successful.
>
> ath9k_htc 1-1.4:1.0: ath9k_htc: HTC initialized with 33 credits
> ath: phy2: Failed to read SREV register
> ath: phy2: Could not read hardware revision
> ath: phy2: Unable to initialize hardware; initialization status: -95
> ath: phy2: Unable to initialize hardware; initialization status: -95
> ath9k_htc: Failed to initialize the device
>
> This helps when debugging by directly showing the first point of
> failure and it could prevent possible errors if a 0x0f.3 revision
> is ever supported.
>
> Signed-off-by: Tim Schumacher <timschumi@gmx.de>

[...]

> - val = REG_READ(ah, AR_SREV) & AR_SREV_ID;
> + srev = REG_READ(ah, AR_SREV);
> +
> + if (srev == -EIO) {
> + ath_err(ath9k_hw_common(ah),
> + "Failed to read SREV register");
> + return false;
> + }

I really don't like how the error handling is implemented in REG_READ().
If the register has value 0xfffffffb (= -EIO ==-5) won't this interpret
that as an error?

--
Kalle Valo

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