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    SubjectRe: [PATCH v3 1/1] scsi: ufs: make UFS Tx lane1 clock optional for QCOM platforms
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    On 10/12/2018 6:42 AM, Can Guo wrote:
    > From: Venkat Gopalakrishnan <venkatg@codeaurora.org>
    >
    > Per Qcom's UFS host controller HW design, the UFS Tx lane1 clock could be
    > muxed with Tx lane0 clock, hence keep Tx lane1 clock optional by ignoring
    > it if it is not provided in device tree. This change also performs some
    > cleanup to lanes per direction checks when enable/disable lane clocks just
    > for symmetry.
    >
    > Signed-off-by: Venkat Gopalakrishnan <venkatg@codeaurora.org>
    > Signed-off-by: Subhash Jadavani <subhashj@codeaurora.org>
    > Signed-off-by: Can Guo <cang@codeaurora.org>
    > ---
    > Changes since v2:
    > - Incorporated review comments from Doug.
    >
    > Changes since v1:
    > - Incorporated review comments from Doug.
    > - Update the commit title and commit message.
    >
    > drivers/scsi/ufs/ufs-qcom.c | 55 ++++++++++++++++++++++++---------------------
    > 1 file changed, 29 insertions(+), 26 deletions(-)
    >
    > diff --git a/drivers/scsi/ufs/ufs-qcom.c b/drivers/scsi/ufs/ufs-qcom.c
    > index 2b38db2..dbc84cb 100644
    > --- a/drivers/scsi/ufs/ufs-qcom.c
    > +++ b/drivers/scsi/ufs/ufs-qcom.c
    > @@ -79,20 +79,28 @@ static int ufs_qcom_get_connected_tx_lanes(struct ufs_hba *hba, u32 *tx_lanes)
    > }
    >
    > static int ufs_qcom_host_clk_get(struct device *dev,
    > - const char *name, struct clk **clk_out)
    > + const char *name, struct clk **clk_out, bool optional)
    > {
    > struct clk *clk;
    > int err = 0;
    >
    > clk = devm_clk_get(dev, name);
    > - if (IS_ERR(clk)) {
    > - err = PTR_ERR(clk);
    > - dev_err(dev, "%s: failed to get %s err %d",
    > - __func__, name, err);
    > - } else {
    > + if (!IS_ERR(clk)) {
    > *clk_out = clk;
    > + return 0;
    > }
    >
    > + err = PTR_ERR(clk);
    > +
    > + if (optional && err == -ENOENT) {
    > + *clk_out = NULL;
    > + return 0;
    > + }
    > +
    > + if (err != -EPROBE_DEFER)
    > + dev_err(dev, "failed to get %s err %d",
    > + name, err);
    > +
    > return err;
    > }
    >
    > @@ -113,11 +121,9 @@ static void ufs_qcom_disable_lane_clks(struct ufs_qcom_host *host)
    > if (!host->is_lane_clks_enabled)
    > return;
    >
    > - if (host->hba->lanes_per_direction > 1)
    > - clk_disable_unprepare(host->tx_l1_sync_clk);
    > + clk_disable_unprepare(host->tx_l1_sync_clk);
    > clk_disable_unprepare(host->tx_l0_sync_clk);
    > - if (host->hba->lanes_per_direction > 1)
    > - clk_disable_unprepare(host->rx_l1_sync_clk);
    > + clk_disable_unprepare(host->rx_l1_sync_clk);
    > clk_disable_unprepare(host->rx_l0_sync_clk);
    >
    > host->is_lane_clks_enabled = false;
    > @@ -141,24 +147,21 @@ static int ufs_qcom_enable_lane_clks(struct ufs_qcom_host *host)
    > if (err)
    > goto disable_rx_l0;
    >
    > - if (host->hba->lanes_per_direction > 1) {
    > - err = ufs_qcom_host_clk_enable(dev, "rx_lane1_sync_clk",
    > + err = ufs_qcom_host_clk_enable(dev, "rx_lane1_sync_clk",
    > host->rx_l1_sync_clk);
    > - if (err)
    > - goto disable_tx_l0;
    > + if (err)
    > + goto disable_tx_l0;
    >
    > - err = ufs_qcom_host_clk_enable(dev, "tx_lane1_sync_clk",
    > + err = ufs_qcom_host_clk_enable(dev, "tx_lane1_sync_clk",
    > host->tx_l1_sync_clk);
    > - if (err)
    > - goto disable_rx_l1;
    > - }
    > + if (err)
    > + goto disable_rx_l1;
    >
    > host->is_lane_clks_enabled = true;
    > goto out;
    >
    > disable_rx_l1:
    > - if (host->hba->lanes_per_direction > 1)
    > - clk_disable_unprepare(host->rx_l1_sync_clk);
    > + clk_disable_unprepare(host->rx_l1_sync_clk);
    > disable_tx_l0:
    > clk_disable_unprepare(host->tx_l0_sync_clk);
    > disable_rx_l0:
    > @@ -172,25 +175,25 @@ static int ufs_qcom_init_lane_clks(struct ufs_qcom_host *host)
    > int err = 0;
    > struct device *dev = host->hba->dev;
    >
    > - err = ufs_qcom_host_clk_get(dev,
    > - "rx_lane0_sync_clk", &host->rx_l0_sync_clk);
    > + err = ufs_qcom_host_clk_get(dev, "rx_lane0_sync_clk",
    > + &host->rx_l0_sync_clk, false);
    > if (err)
    > goto out;
    >
    > - err = ufs_qcom_host_clk_get(dev,
    > - "tx_lane0_sync_clk", &host->tx_l0_sync_clk);
    > + err = ufs_qcom_host_clk_get(dev, "tx_lane0_sync_clk",
    > + &host->tx_l0_sync_clk, false);
    > if (err)
    > goto out;
    >
    > /* In case of single lane per direction, don't read lane1 clocks */
    > if (host->hba->lanes_per_direction > 1) {
    > err = ufs_qcom_host_clk_get(dev, "rx_lane1_sync_clk",
    > - &host->rx_l1_sync_clk);
    > + &host->rx_l1_sync_clk, false);
    > if (err)
    > goto out;
    >
    > err = ufs_qcom_host_clk_get(dev, "tx_lane1_sync_clk",
    > - &host->tx_l1_sync_clk);
    > + &host->tx_l1_sync_clk, true);
    > }
    > out:
    > return err;

    Reviewed-by: Vivek Gautam <vivek.gautam@codeaurora.org>

    Best regards
    Vivek

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