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Tue, 2 Aug 2016 03:16:46 -0700 (MST) Received: from localhost.localdomain ([10.113.62.209]) by mmp1.samsung.com (Oracle Communications Messaging Server 7.0.5.31.0 64bit (built May 5 2014)) with ESMTPA id <0OBA001S41VWQ300@mmp1.samsung.com>; Tue, 02 Aug 2016 19:16:46 +0900 (KST) From: Seung-Woo Kim To: linux-samsung-soc@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, k.kozlowski@samsung.com, thierry.reding@gmail.com, linux-pwm@vger.kernel.org Subject: [PATCH] pwm: samsung: fix to use lowest div for large enough modulation bits Date: Tue, 02 Aug 2016 19:16:46 +0900 Message-id: <1470133006-4272-1-git-send-email-sw0312.kim@samsung.com> X-Mailer: git-send-email 1.7.4.1 X-Brightmail-Tracker: H4sIAAAAAAAAA+NgFjrALMWRmVeSWpSXmKPExsWyRsSkQJeveEG4wb930hYv7l1ksXj9wtBi 0+NrrBaXd81hs7h7dxWjxYzz+5gsZkx+yWbxc9c8FgcOj52z7rJ7bF5S79G3ZRWjx+dNcgEs UVw2Kak5mWWpRfp2CVwZB3Y9ZSnYwV/x4MZGpgbGNzxdjJwcEgImEld/P2SBsMUkLtxbz9bF yMUhJLCCUWLL9xusMEUbLz5mhEgsZZTo3DmdFcL5wSjxePJuNpAqNgEdif1LfoN1iAjsZpRo nK7dxcjBwSxgLHH3kjOIKSwQLrFlAwdIBYuAqsTWVxeZQGxeAVeJ3vdTmSB2KUgsuPcW7AgJ gXZ2iRU7HjNBNAhIfJt8iAVkjoSArMSmA8wQ9ZISB1fcYJnAKLiAkWEVo2hqQXJBcVJ6kaFe cWJucWleul5yfu4mRmDAnv73rHcH4+0D1ocYBTgYlXh4TyguCBdiTSwrrsw9xGgKtGEis5Ro cj4wLvJK4g2NzYwsTE1MjY3MLc2UxHkVpX4GCwmkJ5akZqemFqQWxReV5qQWH2Jk4uCUamBM /d61Ve1c68Ztsk1nRA1nX84vZCxgW2Uyn0Mw89WtFXyPJ69K2MVt21+5oeFZ3ObgUwnP01K6 uqPdO2+VX2CJXufRGWvuwqY1938qe4pgzY4tL6+8v1Hw6DnPqbVNi+T1Cry8/UoXLMxL+Dx5 vtWUdeciPxYtOHPnosrJ0P2FZz2T/C99O7NFiaU4I9FQi7moOBEAwNDsy1MCAAA= X-Brightmail-Tracker: H4sIAAAAAAAAA+NgFuplkeLIzCtJLcpLzFFi42I5/e+xgC5f8YJwg09/RC1e3LvIYvH6haHF psfXWC0u75rDZnH37ipGixnn9zFZzJj8ks3i5655LA4cHjtn3WX32Lyk3qNvyypGj8+b5AJY ohoYbTJSE1NSixRS85LzUzLz0m2VvIPjneNNzQwMdQ0tLcyVFPISc1NtlVx8AnTdMnOArlBS KEvMKQUKBSQWFyvp22GaEBripmsB0xih6xsSBNdjZIAGEtYwZhzY9ZSlYAd/xYMbG5kaGN/w dDFyckgImEhsvPiYEcIWk7hwbz1bFyMXh5DAUkaJzp3TWSGcH4wSjyfvZgOpYhPQkdi/5Dcr iC0isJtRonG6dhcjBwezgLHE3UvOIKawQLjElg0cIBUsAqoSW19dZAKxeQVcJXrfT2WC2KUg seDeW7YJjNwLGBlWMUqkFiQXFCel5xrlpZbrFSfmFpfmpesl5+duYgRHxTPpHYyHd7kfYhTg YFTi4e14OT9ciDWxrLgy9xCjBAezkgivbdGCcCHelMTKqtSi/Pii0pzU4kOMpkAHTGSWEk3O B0ZsXkm8obGJmZGlkbmhhZGxuZI47+P/68KEBNITS1KzU1MLUotg+pg4OKUaGFm/Le7aIJJ0 P+YEwwrDHu0DX7d1nde7/PvQAnFD1WiWBAP17dxd+6U3LNjxR9k5W/xx/NEpnVydYbOkLk38 c3Xf2i/cSfKOd6ccnC7B/9w2x/Nj+LnZIY6VUn/fSb2T+T/nv+6iZ2vYHhbGc3lenulVd3Hm mx8GPO8kdzQysAUJeJqq/bx5TVeJpTgj0VCLuag4EQDl8EPToAIAAA== DLP-Filter: Pass X-MTR: 20000000000000000@CPGS X-CFilter-Loop: Reflected X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20160802_031711_063704_51B57872 X-CRM114-Status: GOOD ( 13.97 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.20 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: sw0312.kim@samsung.com, jy0922.shim@samsung.com MIME-Version: 1.0 Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+patchwork-linux-arm=patchwork.kernel.org@lists.infradead.org X-Virus-Scanned: ClamAV using ClamSMTP From pwm_samsung_calc_tin(), there is routine to find the lowest divider possible to generate lower frequency than requested one. But it is always possible to generate requested frequency with large enough modulation bits, so this patch fixes to use lowest div for the case. This patch removes following UBSAN warning: UBSAN: Undefined behaviour in drivers/pwm/pwm-samsung.c:197:13 shift exponent 32 is too large for 32-bit type 'long unsigned int' [...] [] (ubsan_epilogue) from [] (__ubsan_handle_shift_out_of_bounds+0xd8/0x120) [] (__ubsan_handle_shift_out_of_bounds) from [] (pwm_samsung_config+0x508/0x6a4) [] (pwm_samsung_config) from [] (pwm_apply_state+0x174/0x40c) [] (pwm_apply_state) from [] (pwm_fan_probe+0xc8/0x488) [] (pwm_fan_probe) from [] (platform_drv_probe+0x70/0x150) [...] Signed-off-by: Seung-Woo Kim Reviewed-by: Joonyoung Shim --- The UBSAN warning from ARM is reported with the patch in following link: https://patchwork.kernel.org/patch/9189575/ --- drivers/pwm/pwm-samsung.c | 10 +++++++--- 1 file changed, 7 insertions(+), 3 deletions(-) diff --git a/drivers/pwm/pwm-samsung.c b/drivers/pwm/pwm-samsung.c index ada2d32..ff0def6 100644 --- a/drivers/pwm/pwm-samsung.c +++ b/drivers/pwm/pwm-samsung.c @@ -193,9 +193,13 @@ static unsigned long pwm_samsung_calc_tin(struct samsung_pwm_chip *chip, * divider settings and choose the lowest divisor that can generate * frequencies lower than requested. */ - for (div = variant->div_base; div < 4; ++div) - if ((rate >> (variant->bits + div)) < freq) - break; + if (fls(rate) <= variant->bits) { + div = variant->div_base; + } else { + for (div = variant->div_base; div < 4; ++div) + if ((rate >> (variant->bits + div)) < freq) + break; + } pwm_samsung_set_divisor(chip, chan, BIT(div));