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Date: Mon, 20 Mar 2017 10:53:22 +0100 From: Philipp Zabel <p.zabel@...gutronix.de> To: Andrzej Hajda <a.hajda@...sung.com> Cc: linux-mmc@...r.kernel.org, Jaehoon Chung <jh80.chung@...sung.com>, Ulf Hansson <ulf.hansson@...aro.org>, linux-kernel@...r.kernel.org, "Szyprowski, Marek" <m.szyprowski@...sung.com>, Bartlomiej Zolnierkiewicz <b.zolnierkie@...sung.com> Subject: Re: [PATCH v2 06/14] mmc: dw_mmc: simplify optional reset handling On Mon, 2017-03-20 at 10:22 +0100, Andrzej Hajda wrote: > Hi Philipp, > > Todays next branch does not work with exynos5433-tm2 board. > I guess this patch causes regression. On MMC without reset controller I > get errors: > [ 4.938222] dwmmc_exynos 15540000.mshc: platform data not available > [ 4.943268] dwmmc_exynos: probe of 15540000.mshc failed with error -22 > [ 4.950184] dwmmc_exynos 15560000.mshc: platform data not available > [ 4.955962] dwmmc_exynos: probe of 15560000.mshc failed with error -22 > > Commenting out reset controller get and error checks 'fixes' the issue. > > On 15.03.2017 12:31, Philipp Zabel wrote: > > As of commit bb475230b8e5 ("reset: make optional functions really > > optional"), the reset framework API calls use NULL pointers to describe > > optional, non-present reset controls. > > > > This allows to return errors from devm_reset_control_get_optional and to > > call reset_control_(de)assert unconditionally. > > > > Signed-off-by: Philipp Zabel <p.zabel@...gutronix.de> > > --- > > drivers/mmc/host/dw_mmc.c | 14 +++++--------- > > 1 file changed, 5 insertions(+), 9 deletions(-) > > > > diff --git a/drivers/mmc/host/dw_mmc.c b/drivers/mmc/host/dw_mmc.c > > index a9ac0b4573131..3d62b0a1f81cb 100644 > > --- a/drivers/mmc/host/dw_mmc.c > > +++ b/drivers/mmc/host/dw_mmc.c > > @@ -2968,10 +2968,8 @@ static struct dw_mci_board *dw_mci_parse_dt(struct dw_mci *host) > > > > /* find reset controller when exist */ > > pdata->rstc = devm_reset_control_get_optional(dev, "reset"); > > - if (IS_ERR(pdata->rstc)) { > > - if (PTR_ERR(pdata->rstc) == -EPROBE_DEFER) > > - return ERR_PTR(-EPROBE_DEFER); > > - } > > + if (IS_ERR(pdata->rstc)) > > + return ERR_CAST(pdata->rstc); > > > With three lines above commented out it works. So devm_reset_control_get_optional returns -EINVAL. Why? The mshc@...60000 node is compatible to "samsung,exynos7-dw-mshc-smu", so that's dw_mmc-exynos.c calling dw_mci_pltfm_register, which then calls dw_mci_probe, passing the original platform device as host->dev = &pdev->dev, and I expect __of_reset_control_get being called with a valid DT node (dev->of_node). Since id is set to "reset", of_property_match_string(node, "reset-names", id) should then be called and return -EINVAL because the "reset-names" property does not exist. Then __of_reset_control_get should return NULL because optional == true. Some of this obviously doesn't happen, where am I wrong? regards Philipp
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