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From: takasi-y@ops.dti.ne.jp
To: linux-sh-u79uwXL29TY76Z2rM5mHXA@public.gmane.org
Cc: Simon Horman <horms-/R6kz+dDXgpPR4JQBCEnsQ@public.gmane.org>,
	Magnus Damm <magnus.damm-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>,
	Linus Walleij
	<linus.walleij-QSEj5FYQhm4dnm+yROfE0A@public.gmane.org>,
	Mark Brown <broonie-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>,
	linux-spi-u79uwXL29TY76Z2rM5mHXA@public.gmane.org
Subject: [PATCH 02/11] spi: spi-sh-msiof: round up div to fix freq calculation
Date: Sun, 01 Dec 2013 18:19:13 +0000	[thread overview]
Message-ID: <1385921962-19843-2-git-send-email-takasi-y@ops.dti.ne.jp> (raw)
In-Reply-To: <1385921962-19843-1-git-send-email-takasi-y-nDL5PR/MsHhHfZP73Gtkiw@public.gmane.org>

From: Takashi Yoshii <takasi-y@ops.dti.ne.jp>

Truncation on integer division in sh_msiof_spi_set_clk_regs()
results in insufficient transfer frequency (> max_speed_freq).

For example, source 52MHz, required max 6MHz
 52/6 = 8.6 --> 8, then 1/8 table selected,
and result in 52/8 = 6.5 MHz (>6MHz)

Rounding it up is a simple solution.
 52/6 = 8.6 --> 9, then 1/16 table selected,
and result in 52/16 = 3.25 MHz

Signed-off-by: Takashi Yoshii <takasi-y@ops.dti.ne.jp>
---
 drivers/spi/spi-sh-msiof.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/spi/spi-sh-msiof.c b/drivers/spi/spi-sh-msiof.c
index c74298c..ac8795f 100644
--- a/drivers/spi/spi-sh-msiof.c
+++ b/drivers/spi/spi-sh-msiof.c
@@ -152,7 +152,7 @@ static void sh_msiof_spi_set_clk_regs(struct sh_msiof_spi_priv *p,
 	size_t k;
 
 	if (!WARN_ON(!spi_hz || !parent_rate))
-		div = parent_rate / spi_hz;
+		div = DIV_ROUND_UP(parent_rate, spi_hz);
 
 	/* TODO: make more fine grained */
 
-- 
1.7.9.5


WARNING: multiple messages have this Message-ID (diff)
From: takasi-y-nDL5PR/MsHhHfZP73Gtkiw@public.gmane.org
To: linux-sh-u79uwXL29TY76Z2rM5mHXA@public.gmane.org
Cc: Simon Horman <horms-/R6kz+dDXgpPR4JQBCEnsQ@public.gmane.org>,
	Magnus Damm <magnus.damm-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>,
	Linus Walleij
	<linus.walleij-QSEj5FYQhm4dnm+yROfE0A@public.gmane.org>,
	Mark Brown <broonie-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>,
	linux-spi-u79uwXL29TY76Z2rM5mHXA@public.gmane.org
Subject: [PATCH 02/11] spi: spi-sh-msiof: round up div to fix freq calculation
Date: Mon,  2 Dec 2013 03:19:13 +0900	[thread overview]
Message-ID: <1385921962-19843-2-git-send-email-takasi-y@ops.dti.ne.jp> (raw)
In-Reply-To: <1385921962-19843-1-git-send-email-takasi-y-nDL5PR/MsHhHfZP73Gtkiw@public.gmane.org>

From: Takashi Yoshii <takasi-y-nDL5PR/MsHhHfZP73Gtkiw@public.gmane.org>

Truncation on integer division in sh_msiof_spi_set_clk_regs()
results in insufficient transfer frequency (> max_speed_freq).

For example, source 52MHz, required max 6MHz
 52/6 = 8.6 --> 8, then 1/8 table selected,
and result in 52/8 = 6.5 MHz (>6MHz)

Rounding it up is a simple solution.
 52/6 = 8.6 --> 9, then 1/16 table selected,
and result in 52/16 = 3.25 MHz

Signed-off-by: Takashi Yoshii <takasi-y-nDL5PR/MsHhHfZP73Gtkiw@public.gmane.org>
---
 drivers/spi/spi-sh-msiof.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/spi/spi-sh-msiof.c b/drivers/spi/spi-sh-msiof.c
index c74298c..ac8795f 100644
--- a/drivers/spi/spi-sh-msiof.c
+++ b/drivers/spi/spi-sh-msiof.c
@@ -152,7 +152,7 @@ static void sh_msiof_spi_set_clk_regs(struct sh_msiof_spi_priv *p,
 	size_t k;
 
 	if (!WARN_ON(!spi_hz || !parent_rate))
-		div = parent_rate / spi_hz;
+		div = DIV_ROUND_UP(parent_rate, spi_hz);
 
 	/* TODO: make more fine grained */
 
-- 
1.7.9.5

--
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  parent reply	other threads:[~2013-12-01 18:19 UTC|newest]

Thread overview: 56+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2013-12-01 18:15 [PATCH 00/11] ARM: shmobile: koelsch: MSIOF support Takashi YOSHII
2013-12-01 18:15 ` Takashi YOSHII
2013-12-01 18:19 ` [PATCH 01/11] pinctrl: sh-pfc: r8a7791: fix msiof groups to follow GROUP takasi-y
2013-12-01 18:19   ` takasi-y
2013-12-01 18:19   ` [PATCH 03/11] spi: spi-sh-msiof: let it run even without GPIO takasi-y
2013-12-01 18:19     ` takasi-y
2013-12-02 10:59     ` Sergei Shtylyov
2013-12-02 10:59       ` Sergei Shtylyov
     [not found]     ` <1385921962-19843-3-git-send-email-takasi-y-nDL5PR/MsHhHfZP73Gtkiw@public.gmane.org>
2013-12-02 12:53       ` Mark Brown
2013-12-02 12:53         ` Mark Brown
2013-12-01 18:19   ` [PATCH 04/11] spi: spi-sh-msiof: set hi/low Active for HW CS takasi-y
2013-12-01 18:19     ` takasi-y
     [not found]     ` <1385921962-19843-4-git-send-email-takasi-y-nDL5PR/MsHhHfZP73Gtkiw@public.gmane.org>
2013-12-02 12:54       ` Mark Brown
2013-12-02 12:54         ` Mark Brown
2013-12-01 18:19   ` [PATCH 05/11] spi: spi-sh-msiof: rx_need_dummy_tx variant takasi-y
2013-12-01 18:19     ` takasi-y
     [not found]     ` <1385921962-19843-5-git-send-email-takasi-y-nDL5PR/MsHhHfZP73Gtkiw@public.gmane.org>
2013-12-02 17:49       ` Mark Brown
2013-12-02 17:49         ` Mark Brown
2013-12-01 18:19   ` [PATCH 11/11] ARM: shmobile: koelsch: spidev for r2a11302 takasi-y
2013-12-01 18:19     ` takasi-y
     [not found]     ` <1385921962-19843-11-git-send-email-takasi-y-nDL5PR/MsHhHfZP73Gtkiw@public.gmane.org>
2013-12-02 13:24       ` Mark Brown
2013-12-02 13:24         ` Mark Brown
2014-02-11 15:06         ` Geert Uytterhoeven
2014-02-11 15:06           ` Geert Uytterhoeven
     [not found]   ` <1385921962-19843-1-git-send-email-takasi-y-nDL5PR/MsHhHfZP73Gtkiw@public.gmane.org>
2013-12-01 18:19     ` takasi-y [this message]
2013-12-01 18:19       ` [PATCH 02/11] spi: spi-sh-msiof: round up div to fix freq calculation takasi-y-nDL5PR/MsHhHfZP73Gtkiw
2013-12-02 12:48       ` Mark Brown
2013-12-02 12:48         ` Mark Brown
2013-12-01 18:19     ` [PATCH 06/11] spi: spi-sh-msiof: RMDIR1[15:0] may should be zero takasi-y
2013-12-01 18:19       ` takasi-y-nDL5PR/MsHhHfZP73Gtkiw
2013-12-01 18:19     ` [PATCH 07/11] spi: spi-sh-msiof: RSCR register may absent takasi-y
2013-12-01 18:19       ` takasi-y-nDL5PR/MsHhHfZP73Gtkiw
     [not found]       ` <1385921962-19843-7-git-send-email-takasi-y-nDL5PR/MsHhHfZP73Gtkiw@public.gmane.org>
2014-02-12 16:06         ` Geert Uytterhoeven
2014-02-12 16:06           ` Geert Uytterhoeven
     [not found]           ` <CAMuHMdVVC1deEQfbLzPzU08LYxf=KOtG3oL2_M4HMBGvJE+8KQ-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2014-02-12 23:50             ` Simon Horman
2014-02-12 23:50               ` Simon Horman
2013-12-01 18:19     ` [PATCH 08/11] ARM: shmobile: r8a7791: Add MSIOF clocks takasi-y
2013-12-01 18:19       ` takasi-y-nDL5PR/MsHhHfZP73Gtkiw
2013-12-01 18:19     ` [PATCH 09/11] ARM: shmobile: r8a7791: MSIOF platform device takasi-y
2013-12-01 18:19       ` takasi-y-nDL5PR/MsHhHfZP73Gtkiw
2013-12-03 10:12       ` Linus Walleij
2013-12-03 10:12         ` Linus Walleij
     [not found]         ` <CACRpkdbvrYgRh7cK0N1HrcxkYzzu9Qw4yAoQwj4f9pEf0r1qQw-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2013-12-05  3:02           ` Simon Horman
2013-12-05  3:02             ` Simon Horman
     [not found]             ` <20131205030235.GG21443-/R6kz+dDXgpPR4JQBCEnsQ@public.gmane.org>
2013-12-11 12:27               ` Linus Walleij
2013-12-11 12:27                 ` Linus Walleij
     [not found]                 ` <CACRpkda=m_3Y+FcKUvAj4e1gDUuvqB4VS4bv6u-VnX4LVQQP8Q-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2013-12-12  0:53                   ` Olof Johansson
2013-12-12  0:53                     ` Olof Johansson
2013-12-01 18:19     ` [PATCH 10/11] ARM: shmobile: koelsch: pinctrl map for MSIOF0 takasi-y
2013-12-01 18:19       ` takasi-y-nDL5PR/MsHhHfZP73Gtkiw
2013-12-03 10:13       ` Linus Walleij
2013-12-03 10:13         ` Linus Walleij
2013-12-03 10:08     ` [PATCH 01/11] pinctrl: sh-pfc: r8a7791: fix msiof groups to follow GROUP Linus Walleij
2013-12-03 10:08       ` Linus Walleij
2013-12-04  1:23       ` Laurent Pinchart
2013-12-04  1:23         ` Laurent Pinchart

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