From: Ben Cahill <ben.m.cahill@xxxxxxxxx> Signed-off-by: Ben Cahill <ben.m.cahill@xxxxxxxxx> Signed-off-by: Reinette Chatre <reinette.chatre@xxxxxxxxx> --- drivers/net/wireless/iwlwifi/iwl-io.h | 20 ++++++++++++++++++++ 1 files changed, 20 insertions(+), 0 deletions(-) diff --git a/drivers/net/wireless/iwlwifi/iwl-io.h b/drivers/net/wireless/iwlwifi/iwl-io.h index 0a078b0..d0a358c 100644 --- a/drivers/net/wireless/iwlwifi/iwl-io.h +++ b/drivers/net/wireless/iwlwifi/iwl-io.h @@ -200,6 +200,26 @@ static inline int _iwl_grab_nic_access(struct iwl_priv *priv) /* this bit wakes up the NIC */ _iwl_set_bit(priv, CSR_GP_CNTRL, CSR_GP_CNTRL_REG_FLAG_MAC_ACCESS_REQ); + + /* + * These bits say the device is running, and should keep running for + * at least a short while (at least as long as MAC_ACCESS_REQ stays 1), + * but they do not indicate that embedded SRAM is restored yet; + * 3945 and 4965 have volatile SRAM, and must save/restore contents + * to/from host DRAM when sleeping/waking for power-saving. + * Each direction takes approximately 1/4 millisecond; with this + * overhead, it's a good idea to grab and hold MAC_ACCESS_REQUEST if a + * series of register accesses are expected (e.g. reading Event Log), + * to keep device from sleeping. + * + * CSR_UCODE_DRV_GP1 register bit MAC_SLEEP == 0 indicates that + * SRAM is okay/restored. We don't check that here because this call + * is just for hardware register access; but GP1 MAC_SLEEP check is a + * good idea before accessing 3945/4965 SRAM (e.g. reading Event Log). + * + * 5000 series and later (including 1000 series) have non-volatile SRAM, + * and do not save/restore SRAM when power cycling. + */ ret = _iwl_poll_bit(priv, CSR_GP_CNTRL, CSR_GP_CNTRL_REG_VAL_MAC_ACCESS_EN, (CSR_GP_CNTRL_REG_FLAG_MAC_CLOCK_READY | -- 1.5.6.3 -- To unsubscribe from this list: send the line "unsubscribe linux-wireless" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
