Re: [PATCH v2 2/2] phy: qcom: qmp-pcie: Add PHY register retention support

[Konrad Dybcio]

On 12.02.2025 12:07 PM, Dmitry Baryshkov wrote:
> On Wed, Feb 12, 2025 at 04:31:21PM +0800, Wenbin Yao (Consultant) wrote:
>> On 2/12/2025 8:13 AM, Dmitry Baryshkov wrote:
>>> On Tue, Feb 11, 2025 at 05:42:31PM +0800, Wenbin Yao wrote:
>>>> From: Qiang Yu <quic_qianyu@xxxxxxxxxxx>
>>>>
>>>> Some QCOM PCIe PHYs support no_csr reset. Unlike BCR reset which resets the
>>>> whole PHY (hardware and register), no_csr reset only resets PHY hardware
>>>> but retains register values, which means PHY setting can be skipped during
>>>> PHY init if PCIe link is enabled in booltloader and only no_csr is toggled
>>>> after that.
>>>>
>>>> Hence, determine whether the PHY has been enabled in bootloader by
>>>> verifying QPHY_START_CTRL register. If it's programmed and no_csr reset is
>>>> available, skip BCR reset and PHY register setting to establish the PCIe
>>>> link with bootloader - programmed PHY settings.
>>>>
>>>> Signed-off-by: Qiang Yu <quic_qianyu@xxxxxxxxxxx>
>>>> Signed-off-by: Wenbin Yao <quic_wenbyao@xxxxxxxxxxx>
>>>> ---
>>>>   drivers/phy/qualcomm/phy-qcom-qmp-pcie.c | 91 +++++++++++++++---------
>>>>   1 file changed, 58 insertions(+), 33 deletions(-)
>>>>
> 
>>>> @@ -4042,16 +4057,22 @@ static int qmp_pcie_power_on(struct phy *phy)
>>>>   	unsigned int mask, val;
>>>>   	int ret;
>>>> -	qphy_setbits(pcs, cfg->regs[QPHY_PCS_POWER_DOWN_CONTROL],
>>>> -			cfg->pwrdn_ctrl);
>>>> +	/*
>>>> +	 * Write CSR register for phy that doesn't support no_csr
>>> what is CSR register?
>> The registers of PHY.
> 
> So 'CSR registers for phy' means 'registers of PHY for phy'? that seems
> incorrect.

"Control and Status Registers"

Konrad