On Thu, Apr 23 2009, Jeff Garzik wrote:
> Jens Axboe wrote:
>>> +static void sd_read_block_characteristics(struct scsi_disk *sdkp)
>>> +{
>>> + char *buffer;
>>> + u16 rot;
>>> +
>>> + /* Block Device Characteristics VPD */
>>> + buffer = scsi_get_vpd_page(sdkp->device, 0xb1);
>>> +
>>> + if (buffer == NULL)
>>> + return;
>>> +
>>> + rot = get_unaligned_be16(&buffer[4]);
>>> +
>>> + if (rot == 1)
>>> + queue_flag_set_unlocked(QUEUE_FLAG_NONROT, sdkp->disk->queue);
>>> +
>>> + kfree(buffer);
>>> +}
>>> +
>>> +/**
>>> * sd_revalidate_disk - called the first time a new disk is seen,
>>> * performs disk spin up, read_capacity, etc.
>>> * @disk: struct gendisk we care about
>>> @@ -1836,6 +1860,7 @@ static int sd_revalidate_disk(struct gen
>>> */
>>> if (sdkp->media_present) {
>>> sd_read_capacity(sdkp, buffer);
>>> + sd_read_block_characteristics(sdkp);
>>> sd_read_write_protect_flag(sdkp, buffer);
>>> sd_read_cache_type(sdkp, buffer);
>>> sd_read_app_tag_own(sdkp, buffer);
>>> @@ -1976,6 +2001,8 @@ static void sd_probe_async(void *data, a
>>> add_disk(gd);
>>> sd_dif_config_host(sdkp);
>>> + sd_revalidate_disk(gd);
>>> +
>>> sd_printk(KERN_NOTICE, sdkp, "Attached SCSI %sdisk\n",
>>> sdp->removable ? "removable " : "");
>>
>> Make sure this works for libata as well, and then kill the rotational
>> check in there instead.
>
> Yep. libata-scsi.c would need to simulate that VPD page.
Exactly
> Also (to mkp or whoever does the work) -- note Linus's comment, and my
> provisional patch[1], about libata potentially wanting to detect NONROT
> by looking for "*SSD" from IDENTIFY DEVICE'S model string.
I think that's an entirely orthogonal issue.
>
> Jeff
>
>
> [1] partial subject line, from the big "Ext3 latency fixes" thread):
> "libata: add SSD detection hueristic; move SSD setup to ata_dev_configure"
>
>
--
Jens Axboe
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