Messages in this thread | | | Date | Sat, 30 Aug 2008 22:01:35 +0400 | From | Sergei Shtylyov <> | Subject | Re: [PATCH 1/4] Introduce ata_id_has_unload() |
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Elias Oltmanns wrote:
>>>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.
> Yes, I tend to agree with you and, in fact, I have been leaning in this > direction myself. However, there is something that really bothers me. > Both entries describing bit 13 of word 87 and 84 are worded alike. In > particular, it says *supported* in both places, whereas in the case of the > other features it would say enabled in one and supported in the other > place.
I think it says "supported" where the feature can't be disabled and "enabled" where it can. Otherwise, this would make a little sense indeed. Hm, I even found a quote in ATA/PI-7 rev. 4b backing this claim (should've pasted it into previous mail):
6.17.43 Words (87:85): Features/command sets enabled
Words (87:85) shall indicate features/command sets enabled. If a defined bit is cleared to zero, the indicated features/command set is not enabled. If a supported features/command set is supported and cannot be disabled, it is defined as supported and the bit shall be set to one.
>>>+ */ >>>+ 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...
> Not having too strong an opinion about it, I just thought that an > operator at the beginning of the line was another indication (apart from > indentation) that this still belongs to the condition. Still, I can
Do we need *another* indication? :-)
> change it for the next series round.
> Regards,
> Elias
MBR, Sergei
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