lkml.org 
[lkml]   [2019]   [Mar]   [26]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    /
    From
    SubjectRe: [RESEND] i2c: imx: defer probing on dma channel request
    Date
    Hi Steve,

    Thanks for the review! Few comments inline.

    On 25.03.2019 19:12, Steven Price wrote:
    > On 25/03/2019 15:30, laurentiu.tudor@nxp.com wrote:
    >> From: Laurentiu Tudor <laurentiu.tudor@nxp.com>
    >>
    >> If the dma controller is not yet probed, defer i2c probe.
    >> The error path in probe was slightly modified (no functional change)
    >
    > There is a functional change for cases like:
    >
    >> ret = pm_runtime_get_sync(&pdev->dev);
    >> if (ret < 0)
    >> goto rpm_disable;
    >
    > ...as rpm_disable will no longer fall through to the call of
    > clk_disable_unprepare().

    Good point, I missed that.

    >> to avoid triggering this WARN_ON():
    >> "cg-pll0-div1 already disabled
    >> WARNING: CPU: 1 PID: 1 at drivers/clk/clk.c:828 clk_core_disable+0xa8/0xb0"
    >
    > I'm also not sure how this WARN_ON was hit. i2c_imx_probe() calls
    > clk_prepare_enable() which should increment the reference count. So it
    > should always be possible to decrememt the enable_count. What am I missing?

    I am no longer able to replicate this. Perhaps in the mean time changes
    in the clk core fixed this corner case.

    >> Signed-off-by: Laurentiu Tudor <laurentiu.tudor@nxp.com>
    >> ---
    >> drivers/i2c/busses/i2c-imx.c | 21 +++++++++++++--------
    >> 1 file changed, 13 insertions(+), 8 deletions(-)
    >>
    >> diff --git a/drivers/i2c/busses/i2c-imx.c b/drivers/i2c/busses/i2c-imx.c
    >> index 42fed40198a0..4e34b1572756 100644
    >> --- a/drivers/i2c/busses/i2c-imx.c
    >> +++ b/drivers/i2c/busses/i2c-imx.c
    >> @@ -1111,7 +1111,8 @@ static int i2c_imx_probe(struct platform_device *pdev)
    >> pdev->name, i2c_imx);
    >> if (ret) {
    >> dev_err(&pdev->dev, "can't claim irq %d\n", irq);
    >> - goto clk_disable;
    >> + clk_disable_unprepare(i2c_imx->clk);
    >> + return ret;
    >> }
    >>
    >> /* Init queue */
    >> @@ -1161,19 +1162,25 @@ static int i2c_imx_probe(struct platform_device *pdev)
    >> pm_runtime_mark_last_busy(&pdev->dev);
    >> pm_runtime_put_autosuspend(&pdev->dev);
    >>
    >> + /* Init DMA config if supported */
    >> + ret = i2c_imx_dma_request(i2c_imx, phy_addr);
    >> + if (ret) {
    >> + if (ret != -EPROBE_DEFER)
    >> + dev_info(&pdev->dev, "can't use DMA, using PIO instead.\n");
    >> + else
    >> + goto del_adapter;
    >> + }
    >> +
    >
    > This can be simplified by reversing the condition:

    Well, in the mean time I just found out that this commit [1] fixes the
    issue I was seeing so I think the patch is no longer needed.

    [1]
    https://git.kernel.org/pub/scm/linux/kernel/git/wsa/linux.git/commit/?h=i2c/for-next&id=e1ab9a468e3b1

    ---
    Best Regards, Laurentiu
    \
     
     \ /
      Last update: 2019-03-26 12:53    [W:2.663 / U:0.172 seconds]
    ©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site