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libata: Add the AHCI_HFLAG_NO_WRITE_TO_RO flag 

While most hardware will simply ignore a write to a read-only register,
some hardware will signal an abort if this occurs.

This commit introduces the flag AHCI_HFLAG_NO_WRITE_TO_RO to prevent the
AHCI library from attempting to write to the HOST_CAP, HOST_CAP2, and
HOST_PORTS_IMPL registers which may be read-only.

Signed-off-by: Doug Berger <opendmb@gmail.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
This commit is contained in:
Doug Berger 2017-06-21 16:20:13 -07:00 committed by Tejun Heo
parent ef0da1bf76
commit 7fab72f85d
2 changed files with 4 additions and 1 deletions
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2
drivers/ata/ahci.h
View File

@ -249,6 +249,8 @@ enum {
#endif #endif
AHCI_HFLAG_WAKE_BEFORE_STOP = (1 << 22), /* wake before DMA stop */ AHCI_HFLAG_WAKE_BEFORE_STOP = (1 << 22), /* wake before DMA stop */
AHCI_HFLAG_YES_ALPM = (1 << 23), /* force ALPM cap on */ AHCI_HFLAG_YES_ALPM = (1 << 23), /* force ALPM cap on */
AHCI_HFLAG_NO_WRITE_TO_RO = (1 << 24), /* don't write to read
only registers */
/* ap->flags bits */ /* ap->flags bits */

3
drivers/ata/libahci.c
View File

@ -945,7 +945,8 @@ int ahci_reset_controller(struct ata_host *host)
/* Some registers might be cleared on reset. Restore /* Some registers might be cleared on reset. Restore
* initial values. * initial values.
*/ */
ahci_restore_initial_config(host); if (!(hpriv->flags & AHCI_HFLAG_NO_WRITE_TO_RO))
ahci_restore_initial_config(host);
} else } else
dev_info(host->dev, "skipping global host reset\n"); dev_info(host->dev, "skipping global host reset\n");