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    Subject[PATCH 4.19 280/639] media: davinci-isif: avoid uninitialized variable use
    Date
    From: Arnd Bergmann <arnd@arndb.de>

    [ Upstream commit 0e633f97162c1c74c68e2eb20bbd9259dce87cd9 ]

    clang warns about a possible variable use that gcc never
    complained about:

    drivers/media/platform/davinci/isif.c:982:32: error: variable 'frame_size' is uninitialized when used here
    [-Werror,-Wuninitialized]
    dm365_vpss_set_pg_frame_size(frame_size);
    ^~~~~~~~~~
    drivers/media/platform/davinci/isif.c:887:2: note: variable 'frame_size' is declared here
    struct vpss_pg_frame_size frame_size;
    ^
    1 error generated.

    There is no initialization for this variable at all, and there
    has never been one in the mainline kernel, so we really should
    not put that stack data into an mmio register.

    On the other hand, I suspect that gcc checks the condition
    more closely and notices that the global
    isif_cfg.bayer.config_params.test_pat_gen flag is initialized
    to zero and never written to from any code path, so anything
    depending on it can be eliminated.

    To shut up the clang warning, just remove the dead code manually,
    it has probably never been used because any attempt to do so
    would have resulted in undefined behavior.

    Fixes: 63e3ab142fa3 ("V4L/DVB: V4L - vpfe capture - source for ISIF driver on DM365")

    Signed-off-by: Arnd Bergmann <arnd@arndb.de>
    Reviewed-by: Nathan Chancellor <natechancellor@gmail.com>
    Acked-by: Lad, Prabhakar <prabhakar.csengg@gmail.com>
    Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
    Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>
    Signed-off-by: Sasha Levin <sashal@kernel.org>
    ---
    drivers/media/platform/davinci/isif.c | 9 ---------
    1 file changed, 9 deletions(-)

    diff --git a/drivers/media/platform/davinci/isif.c b/drivers/media/platform/davinci/isif.c
    index 340f8218f54d3..80fa60a4c4489 100644
    --- a/drivers/media/platform/davinci/isif.c
    +++ b/drivers/media/platform/davinci/isif.c
    @@ -884,9 +884,7 @@ static int isif_set_hw_if_params(struct vpfe_hw_if_param *params)
    static int isif_config_ycbcr(void)
    {
    struct isif_ycbcr_config *params = &isif_cfg.ycbcr;
    - struct vpss_pg_frame_size frame_size;
    u32 modeset = 0, ccdcfg = 0;
    - struct vpss_sync_pol sync;

    dev_dbg(isif_cfg.dev, "\nStarting isif_config_ycbcr...");

    @@ -974,13 +972,6 @@ static int isif_config_ycbcr(void)
    /* two fields are interleaved in memory */
    regw(0x00000249, SDOFST);

    - /* Setup test pattern if enabled */
    - if (isif_cfg.bayer.config_params.test_pat_gen) {
    - sync.ccdpg_hdpol = params->hd_pol;
    - sync.ccdpg_vdpol = params->vd_pol;
    - dm365_vpss_set_sync_pol(sync);
    - dm365_vpss_set_pg_frame_size(frame_size);
    - }
    return 0;
    }

    --
    2.20.1


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