Re: Multiple errors with DVD drive

[Damien Le Moal <damien.lemoal@opensource.wdc.com>]

On 9/21/22 21:38, J.J. Berkhout wrote:
> Hello,
> 
> 
> 
> On 21-09-2022 13:58, Niklas Cassel wrote:
>> Another way do disable lpm is to do:
>>
>> $ ls -al /sys/class/scsi_host/host*
>>
>> Find your device in the list. My device is:
>> /sys/class/scsi_host/host13/
>>
>> Print the current lpm policy for your device:
>> $ cat /sys/class/scsi_host/host13/link_power_management_policy
>> med_power_with_dipm
>>
>> Anything other than "max_performance" means that you have (a varying degree)
>> of low power modes enabled.
>>
>> $ sudo sh -c "echo max_performance > /sys/class/scsi_host/host13/link_power_management_policy"
>>
>> $ cat /sys/class/scsi_host/host13/link_power_management_policy 
>> max_performance
>>
>> Try reading from the optical drive after ensuring that the policy is
>> "max_performance".
>>
> 
> Yes, this worked and did the trick!  Reading without any errors.  I did
> not yet try to write, but will do so today.
> When booting with libata.force=nolpm  the link_power_management_policy
> was still med_power_with_dipm and I got the dmesg:
> 
> [    0.291452] ata: failed to parse force parameter "nolpm" (unknown value)

What kernel version are you running ? This should work with the latest
kernels. Your kernel likely pre-dates the addition of all the ata horkage
flag as boot parameter options, which I think was with 5.18 kernel.

> 
> so the ineffectiveness of this boot parameter seems to be explained.
> Might there be some other syntax for this parameter?
> 
> Nevertheless, my problem now has a work-around and I am very happy.
>  Thanks, Niklas.
> 
> Kind regards,
> 
> Jaap Berkhout

-- 
Damien Le Moal
Western Digital Research