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[75.76.18.234]) by smtp.gmail.com with ESMTPSA id bi4-20020a05620a318400b006ef1a8f1b81sm753851qkb.5.2022.11.24.03.53.55 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 24 Nov 2022 03:53:55 -0800 (PST) From: Nathan Barrett-Morrison To: broonie@kernel.org Cc: greg.malysa@timesys.com, linux-kernel@vger.kernel.org, linux-spi@vger.kernel.org, nathan.morrison@timesys.com Subject: RE: [PATCH] spi: cadence-quadspi: Add upper limit safety check to baudrate divisor Date: Thu, 24 Nov 2022 06:53:54 -0500 Message-Id: <20221124115354.132832-1-nathan.morrison@timesys.com> X-Mailer: git-send-email 2.30.2 In-Reply-To: References: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Spam-Status: No, score=-1.9 required=5.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,RCVD_IN_DNSWL_NONE,SPF_HELO_NONE,SPF_PASS autolearn=ham autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on lindbergh.monkeyblade.net Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Mark & Dhruva, Your understanding is correct. This is just checking if the divisor field has exceed the bit field's full scale (0xF) in this case. This was observed when we had a reference block of 500MHz and a max SPI clock of 10MHz setting. 500000000/2*10000000 = 25 25 > 0xF (15) Would you like me to add a dev_err (or such) bailout error condition and resubmit? Sincerely, Nathan