Messages in this thread | | | Date | Sat, 30 Aug 2008 15:56:42 +0400 | From | Sergei Shtylyov <> | Subject | Re: [PATCH 1/4] Introduce ata_id_has_unload() |
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Hello.
Elias Oltmanns wrote:
> Add a function to check an ATA device's id for head unload support as > specified in ATA-7. > > Signed-off-by: Elias Oltmanns <eo@nebensachen.de> > [...] > diff --git a/include/linux/ata.h b/include/linux/ata.h > index 80364b6..d9a94bd 100644 > --- a/include/linux/ata.h > +++ b/include/linux/ata.h > @@ -707,6 +707,23 @@ static inline int ata_id_has_dword_io(const u16 *id) > return 0; > } > > +static inline int ata_id_has_unload(const u16 *id) > +{ > + /* > + * ATA-7 specifies two places to indicate unload feature > + * support. Since I don't really understand the difference, > + * I'll just check both and only return zero if none of them > + * indicates otherwise. >
If you read the comments to the words 82:84 and 85:87, they say that the former indicate the supported features, and the latter indicate the enabed features AND in case a feature can't be disabled, the latter words will have the corresponding bit set. So it should be sufficient to check only one word.
> + */ > + if (ata_id_major_version(id) >= 7 > + && (((id[ATA_ID_CFSSE] & 0xC000) == 0x4000 > + && id[ATA_ID_CFSSE] & (1 << 13)) > + || ((id[ATA_ID_CSF_DEFAULT] & 0xC000) == 0x4000 > + && (id[ATA_ID_CSF_DEFAULT] & (1 << 13))))) >
I think that it's preferrable to leave the operator on the same line with the first operand...
WBR, Sergei
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