Re: [PATCH 4/4] mfd: intel-m10-bmc: Manage access to MAX 10 fw handshake registers

[Xu Yilun]

On 2023-04-05 at 11:01:52 +0300, Ilpo Järvinen wrote:
> On some MAX 10 cards, the BMC firmware is not available to service
> handshake registers during secure update erase and write phases at
> normal speeds. This problem affects at least hwmon driver. When the MAX
> 10 hwmon driver tries to read the sensor values during a secure update,
> the reads are slowed down (e.g., reading all D5005 sensors takes ~24s
> which is magnitudes worse than the normal <0.02s).
> 
> Manage access to the handshake registers using a rw semaphore and a FW
> state variable to prevent accesses during those secure update phases
> and return -EBUSY instead.
> 
> Co-developed-by: Russ Weight <russell.h.weight@xxxxxxxxx>
> Signed-off-by: Russ Weight <russell.h.weight@xxxxxxxxx>
> Co-developed-by: Xu Yilun <yilun.xu@xxxxxxxxx>
> Signed-off-by: Xu Yilun <yilun.xu@xxxxxxxxx>
> Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@xxxxxxxxxxxxxxx>
> ---
>  drivers/fpga/intel-m10-bmc-sec-update.c | 17 +++++--
>  drivers/mfd/intel-m10-bmc-core.c        | 63 ++++++++++++++++++++++++-
>  drivers/mfd/intel-m10-bmc-pmci.c        |  4 ++
>  drivers/mfd/intel-m10-bmc-spi.c         | 14 ++++++
>  include/linux/mfd/intel-m10-bmc.h       | 27 +++++++++++
>  5 files changed, 120 insertions(+), 5 deletions(-)
>

[...]
 
>  
> +void m10bmc_fw_state_set(struct intel_m10bmc *m10bmc, enum m10bmc_fw_state new_state)
> +{
> +	down_write(&m10bmc->bmcfw_lock);
> +	m10bmc->bmcfw_state = new_state;
> +	up_write(&m10bmc->bmcfw_lock);

Could we also skip this if no handshake is possible like for PMCI?

Thanks,
Yilun