Hi, Fei: Fei Shao <fshao@xxxxxxxxxxxx> 於 2024年12月4日 週三 下午10:26寫道： > > The DP calibration data is stored in nvmem cells, and the data layout is > described in the `mtk_dp_efuse_fmt` arrays for each platform. > > There is no guarantee that the data is always a 4-length u32 cell array. > For example, MT8188 has a data length of 3, preventing it from passing > the preliminary check and undergoing calibration. > > Update the logic to support flexible data lengths. Specifically, we > validate the length returned from `nvmem_cell_read()` against the > platform-specific efuse format. If out-of-bound access is detected, fall > back to the default calibration values. This likely indicates an error > in either the efuse data length described in DT or the efuse format > within the driver. Applied to mediatek-drm-next [1], thanks. [1] https://git.kernel.org/pub/scm/linux/kernel/git/chunkuang.hu/linux.git/log/?h=mediatek-drm-next Regards, Chun-Kuang. > > Signed-off-by: Fei Shao <fshao@xxxxxxxxxxxx> > --- > > Changes in v2: > - use %zu identifier for size_t in dev_warn() > > drivers/gpu/drm/mediatek/mtk_dp.c | 18 +++++++++++++----- > 1 file changed, 13 insertions(+), 5 deletions(-) > > diff --git a/drivers/gpu/drm/mediatek/mtk_dp.c b/drivers/gpu/drm/mediatek/mtk_dp.c > index 36713c176cfc..55671701459a 100644 > --- a/drivers/gpu/drm/mediatek/mtk_dp.c > +++ b/drivers/gpu/drm/mediatek/mtk_dp.c > @@ -1165,17 +1165,25 @@ static void mtk_dp_get_calibration_data(struct mtk_dp *mtk_dp) > buf = (u32 *)nvmem_cell_read(cell, &len); > nvmem_cell_put(cell); > > - if (IS_ERR(buf) || ((len / sizeof(u32)) != 4)) { > + if (IS_ERR(buf)) { > dev_warn(dev, "Failed to read nvmem_cell_read\n"); > - > - if (!IS_ERR(buf)) > - kfree(buf); > - > goto use_default_val; > } > > + /* The cell length is in bytes. Convert it to be compatible with u32 buffer. */ > + len /= sizeof(u32); > + > for (i = 0; i < MTK_DP_CAL_MAX; i++) { > fmt = &mtk_dp->data->efuse_fmt[i]; > + > + if (fmt->idx >= len) { > + dev_warn(mtk_dp->dev, > + "Out-of-bound efuse data access, fmt idx = %d, buf len = %zu\n", > + fmt->idx, len); > + kfree(buf); > + goto use_default_val; > + } > + > cal_data[i] = (buf[fmt->idx] >> fmt->shift) & fmt->mask; > > if (cal_data[i] < fmt->min_val || cal_data[i] > fmt->max_val) { > -- > 2.47.0.338.g60cca15819-goog >
