Hi Dan,
We have to program the device with the page size so it knows where the page boundaries are.
I could put all this on one logical line like this:
dev->ctrl_config = NVME_CC_ENABLE | NVME_CC_CSS_NVM |
((PAGE_SHIFT - 12) << NVME_CC_MPS_SHIFT |
NVME_CC_ARB_RR | NVME_CC_SHN_NONE |
NVME_CC_IOSQES | NVME_CC_IOCQES;
in order to shut up the warning, but is that really more readable?
________________________________________
From: Dan Carpenter [dan.carpenter@xxxxxxxxxx]
Sent: June 7, 2013 4:45 AM
To: Wilcox, Matthew R
Cc: kernel-janitors@xxxxxxxxxxxxxxx; Busch, Keith; Verma, Vishal L; Dave Jones
Subject: puzzling code in nvme_configure_admin_queue()
Hi Matthew,
The patch b60503ba432b: "NVMe: New driver" from Jan 20, 2011, leads
to the following warning:
"drivers/block/nvme-core.c:1174 nvme_configure_admin_queue()
warn: foo |= 0"
drivers/block/nvme-core.c
1173 dev->ctrl_config = NVME_CC_ENABLE | NVME_CC_CSS_NVM;
1174 dev->ctrl_config |= (PAGE_SHIFT - 12) << NVME_CC_MPS_SHIFT;
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
How is this used? Most of the time PAGE_SHIFT is 12 so this
statement is a no-op. I searched for NVME_CC_MPS_SHIFT but I didn't
find anything.
1175 dev->ctrl_config |= NVME_CC_ARB_RR | NVME_CC_SHN_NONE;
1176 dev->ctrl_config |= NVME_CC_IOSQES | NVME_CC_IOCQES;
regards,
dan carpenter
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