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[24.205.208.113]) by smtp.gmail.com with ESMTPSA id d15-20020a05622a15cf00b002de711a190bsm4066708qty.71.2022.03.04.13.04.02 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 04 Mar 2022 13:04:05 -0800 (PST) From: trix@redhat.com To: jani.nikula@linux.intel.com, joonas.lahtinen@linux.intel.com, rodrigo.vivi@intel.com, tvrtko.ursulin@linux.intel.com, airlied@linux.ie, daniel@ffwll.ch, nathan@kernel.org, ndesaulniers@google.com, ville.syrjala@linux.intel.com, matthew.d.roper@intel.com, lucas.demarchi@intel.com, airlied@redhat.com, imre.deak@intel.com Cc: intel-gfx@lists.freedesktop.org, dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org, llvm@lists.linux.dev, Tom Rix Subject: [PATCH] drm/i915: rework the error handling in *_dpll_params Date: Fri, 4 Mar 2022 13:03:55 -0800 Message-Id: <20220304210355.608898-1-trix@redhat.com> X-Mailer: git-send-email 2.26.3 MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" From: Tom Rix Clang static analysis reports this issue intel_dpll.c:472:31: warning: The left operand of '-' is a garbage value [core.UndefinedBinaryOperatorResult] this_err =3D abs(clock.dot - target); ~~~~~~~~~ ^ In a loop clock.dot is set on successful call to i9xx_calc_dpll_params(). If the call fails, the later *is_valid() will use the previous loop's clock.dot. The *_dpll_params functions return an arithmetic statement with the clock.dot as the variable. Change the error handler to set clock.dot to 0 and jump to the return statement. Fixes: dccbea3b0704 ("drm/i915: calculate the port clock rate along with ot= her PLL params") Signed-off-by: Tom Rix --- drivers/gpu/drm/i915/display/intel_dpll.c | 32 ++++++++++++++--------- 1 file changed, 20 insertions(+), 12 deletions(-) diff --git a/drivers/gpu/drm/i915/display/intel_dpll.c b/drivers/gpu/drm/i9= 15/display/intel_dpll.c index 0ae37fdbf2a5b..ba7cada704288 100644 --- a/drivers/gpu/drm/i915/display/intel_dpll.c +++ b/drivers/gpu/drm/i915/display/intel_dpll.c @@ -309,11 +309,13 @@ int pnv_calc_dpll_params(int refclk, struct dpll *clo= ck) { clock->m =3D clock->m2 + 2; clock->p =3D clock->p1 * clock->p2; - if (WARN_ON(clock->n =3D=3D 0 || clock->p =3D=3D 0)) - return 0; + if (WARN_ON(clock->n =3D=3D 0 || clock->p =3D=3D 0)) { + clock->dot =3D 0; + goto end; + } clock->vco =3D DIV_ROUND_CLOSEST(refclk * clock->m, clock->n); clock->dot =3D DIV_ROUND_CLOSEST(clock->vco, clock->p); - +end: return clock->dot; } =20 @@ -326,11 +328,13 @@ int i9xx_calc_dpll_params(int refclk, struct dpll *cl= ock) { clock->m =3D i9xx_dpll_compute_m(clock); clock->p =3D clock->p1 * clock->p2; - if (WARN_ON(clock->n + 2 =3D=3D 0 || clock->p =3D=3D 0)) - return 0; + if (WARN_ON(clock->n + 2 =3D=3D 0 || clock->p =3D=3D 0)) { + clock->dot =3D 0; + goto end; + } clock->vco =3D DIV_ROUND_CLOSEST(refclk * clock->m, clock->n + 2); clock->dot =3D DIV_ROUND_CLOSEST(clock->vco, clock->p); - +end: return clock->dot; } =20 @@ -338,11 +342,13 @@ int vlv_calc_dpll_params(int refclk, struct dpll *clo= ck) { clock->m =3D clock->m1 * clock->m2; clock->p =3D clock->p1 * clock->p2; - if (WARN_ON(clock->n =3D=3D 0 || clock->p =3D=3D 0)) - return 0; + if (WARN_ON(clock->n =3D=3D 0 || clock->p =3D=3D 0)) { + clock->dot =3D 0; + goto end; + } clock->vco =3D DIV_ROUND_CLOSEST(refclk * clock->m, clock->n); clock->dot =3D DIV_ROUND_CLOSEST(clock->vco, clock->p); - +end: return clock->dot / 5; } =20 @@ -350,12 +356,14 @@ int chv_calc_dpll_params(int refclk, struct dpll *clo= ck) { clock->m =3D clock->m1 * clock->m2; clock->p =3D clock->p1 * clock->p2; - if (WARN_ON(clock->n =3D=3D 0 || clock->p =3D=3D 0)) - return 0; + if (WARN_ON(clock->n =3D=3D 0 || clock->p =3D=3D 0)) { + clock->dot =3D 0; + goto end; + } clock->vco =3D DIV_ROUND_CLOSEST_ULL(mul_u32_u32(refclk, clock->m), clock->n << 22); clock->dot =3D DIV_ROUND_CLOSEST(clock->vco, clock->p); - +end: return clock->dot / 5; } =20 --=20 2.26.3