[PATCH] nvme: Enable FUA

[Jon Lin]

On 2021/9/27 20:28, Stefan Agner wrote:
> On 2021-09-26 11:12, Jon Lin wrote:
>> Most NVME devcies maintain data in internal cache for an uncertain
>> times, and u-boot has no method to force NVME to flush cache.
>> So this patch adds FUA to avoid data loss caused by power off after data
>> programming.
> Maybe worth mentioning that FUA stands for Force Unit Access and makes
> sure that data has been written to non-volatile storage before command
> completion.
>
> It seems to me that volatile cache needs to be explicitly enabled by the
> Volatile Write Cache feature. But I guess it could be already enabled by
> earlier firmware/on reboot? Setting the FUA bit will make certain that
> data land on non-volatile storage in any case. So:
>
> Reviewed-by: Stefan Agner <stefan at agner.ch>
>
> Out of curiosity, has this been a problem in a real world situation?

We are trying to interact with the host computer in the device u-boot 
stage, involving nvme

upgrade and device reset. When the two progress are continuous, there 
are corresponding problems.

> --
> Stefan
>
>> Signed-off-by: Jon Lin <jon.lin at rock-chips.com>
>> ---
>>
>>   drivers/nvme/nvme.c | 3 +++
>>   1 file changed, 3 insertions(+)
>>
>> diff --git a/drivers/nvme/nvme.c b/drivers/nvme/nvme.c
>> index f6465ea7f4..5d05cb6e9e 100644
>> --- a/drivers/nvme/nvme.c
>> +++ b/drivers/nvme/nvme.c
>> @@ -761,6 +761,9 @@ static ulong nvme_blk_rw(struct udevice *udev,
>> lbaint_t blknr,
>>   	c.rw.appmask = 0;
>>   	c.rw.metadata = 0;
>>   
>> +	/* Always enable FUA for data integrity */
>> +	c.rw.control |= NVME_RW_FUA;
>> +
>>   	while (total_lbas) {
>>   		if (total_lbas < lbas) {
>>   			lbas = (u16)total_lbas;
>
>