• Florian Fainelli's avatar
    ata: ahci_brcm: Recover from failures to identify devices · eb73390a
    Florian Fainelli authored
    When powering up, the SATA controller may fail to mount the HDD. The SATA
    controller will lock up, preventing it from negotiating to a lower speed or
    transmitting data. Root cause is power supply noise creating resonance at 6 Ghz
    and 3 GHz frequencies, which causes instability in the Clock-Data Recovery
    (CDR) frontend module, resulting in false acquisition of the clock at SATA
    6G/3G speeds.
    
    The SATA controller may fail to mount the HDD and lock up, requiring a power
    cycle. Broadcom chips suspected of being susceptible to this issue include
    BCM7445, BCM7439, and BCM7366.
    
    The Kernel implements an error recovery mechanism that resets the SATA PHY and
    digital controller when the controller locks up. During this error recovery
    process, typically there is less activity on the board and Broadcom STB chip,
    so that the power supply is less noisy, thus allowing the SATA controller to
    lock correctly.
    Signed-off-by: default avatarFlorian Fainelli <f.fainelli@gmail.com>
    Signed-off-by: default avatarTejun Heo <tj@kernel.org>
    eb73390a
ahci_brcm.c 12.8 KB