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cxl: Check if PSL data-cache is available before issue flush request

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PSL9D doesn't have a data-cache that needs to be flushed before
resetting the card. However when cxl tries to flush data-cache on such
a card, it times-out as PSL_Control register never indicates flush
operation complete due to missing data-cache. This is usually
indicated in the kernel logs with this message:

"WARNING: cache flush timed out"

To fix this the patch checks PSL_Debug register CDC-Field(BIT:27)
which indicates the absence of a data-cache and sets a flag
'no_data_cache' in 'struct cxl_native' to indicate this. When
cxl_data_cache_flush() is called it checks the flag and if set bails
out early without requesting a data-cache flush operation to the PSL.

Signed-off-by: Vaibhav Jain <vaibhav@linux.vnet.ibm.com>
Acked-by: Andrew Donnellan <andrew.donnellan@au1.ibm.com>
Acked-by: Frederic Barrat <fbarrat@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
This commit is contained in:
Vaibhav Jain
2018-02-15 21:19:24 +05:30
committed by Michael Ellerman
parent 02b63b4202
commit 94322ed8e8
3 changed files with 27 additions and 7 deletions
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11
drivers/misc/cxl/native.c
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@@ -353,8 +353,17 @@ int cxl_data_cache_flush(struct cxl *adapter)
u64 reg;
unsigned long timeout = jiffies + (HZ * CXL_TIMEOUT);
pr_devel("Flushing data cache\n");
/*
* Do a datacache flush only if datacache is available.
* In case of PSL9D datacache absent hence flush operation.
* would timeout.
*/
if (adapter->native->no_data_cache) {
pr_devel("No PSL data cache. Ignoring cache flush req.\n");
return 0;
}
pr_devel("Flushing data cache\n");
reg = cxl_p1_read(adapter, CXL_PSL_Control);
reg |= CXL_PSL_Control_Fr;
cxl_p1_write(adapter, CXL_PSL_Control, reg);