* [PATCH v2 2/2] spi: dw: round up result of calculation for clock divider @ 2016-09-04 0:05 Matthias Seidel 2016-09-06 10:53 ` Mark Brown 0 siblings, 1 reply; 6+ messages in thread From: Matthias Seidel @ 2016-09-04 0:05 UTC (permalink / raw) To: Mark Brown; +Cc: linux-spi-u79uwXL29TY76Z2rM5mHXA Avoid ending up with a higher frequency than requested Signed-off-by: Matthias Seidel <kernel-NoMTM8u0nx3R7s880joybQ@public.gmane.org> --- Previously failing example: requested transfer freq: 16MHz max_freq = 200MHz calculated clk_div = 12 actual frequency = 200/12 = 16.6666MHz --- drivers/spi/spi-dw.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/drivers/spi/spi-dw.c b/drivers/spi/spi-dw.c index c85e4b3..2fd517d 100644 --- a/drivers/spi/spi-dw.c +++ b/drivers/spi/spi-dw.c @@ -300,7 +300,8 @@ static int dw_spi_transfer_one(struct spi_master *master, if (transfer->speed_hz != dws->current_freq) { if (transfer->speed_hz != chip->speed_hz) { /* clk_div doesn't support odd number */ - chip->clk_div = (dws->max_freq / transfer->speed_hz + 1) & 0xfffe; + chip->clk_div = ((dws->max_freq + transfer->speed_hz) / + transfer->speed_hz + 1) & 0xfffe; chip->speed_hz = transfer->speed_hz; } dws->current_freq = transfer->speed_hz; -- 2.7.4 -- To unsubscribe from this list: send the line "unsubscribe linux-spi" in the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org More majordomo info at http://vger.kernel.org/majordomo-info.html ^ permalink raw reply related [flat|nested] 6+ messages in thread
* Re: [PATCH v2 2/2] spi: dw: round up result of calculation for clock divider 2016-09-04 0:05 [PATCH v2 2/2] spi: dw: round up result of calculation for clock divider Matthias Seidel @ 2016-09-06 10:53 ` Mark Brown [not found] ` <20160906105352.GK3950-GFdadSzt00ze9xe1eoZjHA@public.gmane.org> 0 siblings, 1 reply; 6+ messages in thread From: Mark Brown @ 2016-09-06 10:53 UTC (permalink / raw) To: Matthias Seidel; +Cc: linux-spi-u79uwXL29TY76Z2rM5mHXA [-- Attachment #1: Type: text/plain, Size: 463 bytes --] On Sun, Sep 04, 2016 at 02:05:35AM +0200, Matthias Seidel wrote: > /* clk_div doesn't support odd number */ > - chip->clk_div = (dws->max_freq / transfer->speed_hz + 1) & 0xfffe; > + chip->clk_div = ((dws->max_freq + transfer->speed_hz) / > + transfer->speed_hz + 1) & 0xfffe; Can we not use DIV_ROUND_UP here if that's what we're trying to do? The above probably needs a comment if not, I'm finding the intent rather confusing looking at the code. [-- Attachment #2: signature.asc --] [-- Type: application/pgp-signature, Size: 455 bytes --] ^ permalink raw reply [flat|nested] 6+ messages in thread
[parent not found: <20160906105352.GK3950-GFdadSzt00ze9xe1eoZjHA@public.gmane.org>]
* [PATCH v3 2/2] spi: dw: round up result of calculation for clock divider [not found] ` <20160906105352.GK3950-GFdadSzt00ze9xe1eoZjHA@public.gmane.org> @ 2016-09-06 17:16 ` Matthias Seidel 2016-09-06 22:21 ` Mark Brown 2016-09-12 19:08 ` Applied "spi: dw: round up result of calculation for clock divider" to the spi tree Mark Brown 0 siblings, 2 replies; 6+ messages in thread From: Matthias Seidel @ 2016-09-06 17:16 UTC (permalink / raw) To: Mark Brown; +Cc: linux-spi-u79uwXL29TY76Z2rM5mHXA Avoid ending up with a higher frequency than requested Signed-off-by: Matthias Seidel <kernel-NoMTM8u0nx3R7s880joybQ@public.gmane.org> --- Previously failing example: requested transfer freq: 16MHz max_freq = 200MHz calculated clk_div = 12 actual frequency = 200/12 = 16.6666MHz v3: I wasn't aware of this macro, better readability. --- drivers/spi/spi-dw.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/spi/spi-dw.c b/drivers/spi/spi-dw.c index c85e4b3..27960e4 100644 --- a/drivers/spi/spi-dw.c +++ b/drivers/spi/spi-dw.c @@ -300,7 +300,7 @@ static int dw_spi_transfer_one(struct spi_master *master, if (transfer->speed_hz != dws->current_freq) { if (transfer->speed_hz != chip->speed_hz) { /* clk_div doesn't support odd number */ - chip->clk_div = (dws->max_freq / transfer->speed_hz + 1) & 0xfffe; + chip->clk_div = (DIV_ROUND_UP(dws->max_freq, transfer->speed_hz) + 1) & 0xfffe; chip->speed_hz = transfer->speed_hz; } dws->current_freq = transfer->speed_hz; -- 2.7.4 -- To unsubscribe from this list: send the line "unsubscribe linux-spi" in the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org More majordomo info at http://vger.kernel.org/majordomo-info.html ^ permalink raw reply related [flat|nested] 6+ messages in thread
* Re: [PATCH v3 2/2] spi: dw: round up result of calculation for clock divider 2016-09-06 17:16 ` [PATCH v3 " Matthias Seidel @ 2016-09-06 22:21 ` Mark Brown [not found] ` <20160906222131.GT3950-GFdadSzt00ze9xe1eoZjHA@public.gmane.org> 2016-09-12 19:08 ` Applied "spi: dw: round up result of calculation for clock divider" to the spi tree Mark Brown 1 sibling, 1 reply; 6+ messages in thread From: Mark Brown @ 2016-09-06 22:21 UTC (permalink / raw) To: Matthias Seidel; +Cc: linux-spi-u79uwXL29TY76Z2rM5mHXA [-- Attachment #1: Type: text/plain, Size: 151 bytes --] On Tue, Sep 06, 2016 at 07:16:52PM +0200, Matthias Seidel wrote: > Avoid ending up with a higher frequency than requested I'm missing patch 1/2 here? [-- Attachment #2: signature.asc --] [-- Type: application/pgp-signature, Size: 455 bytes --] ^ permalink raw reply [flat|nested] 6+ messages in thread
[parent not found: <20160906222131.GT3950-GFdadSzt00ze9xe1eoZjHA@public.gmane.org>]
* [PATCH v4] spi: dw: round up result of calculation for clock divider [not found] ` <20160906222131.GT3950-GFdadSzt00ze9xe1eoZjHA@public.gmane.org> @ 2016-09-07 15:45 ` Matthias Seidel 0 siblings, 0 replies; 6+ messages in thread From: Matthias Seidel @ 2016-09-07 15:45 UTC (permalink / raw) To: Mark Brown; +Cc: linux-spi-u79uwXL29TY76Z2rM5mHXA Avoid ending up with a higher frequency than requested Signed-off-by: Matthias Seidel <kernel-NoMTM8u0nx3R7s880joybQ@public.gmane.org> --- v4: Corrected subject, thanks for your work! Previously failing example: requested transfer freq: 16MHz max_freq = 200MHz calculated clk_div = 12 actual frequency = 200/12 = 16.6666MHz --- drivers/spi/spi-dw.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/spi/spi-dw.c b/drivers/spi/spi-dw.c index c85e4b3..27960e4 100644 --- a/drivers/spi/spi-dw.c +++ b/drivers/spi/spi-dw.c @@ -300,7 +300,7 @@ static int dw_spi_transfer_one(struct spi_master *master, if (transfer->speed_hz != dws->current_freq) { if (transfer->speed_hz != chip->speed_hz) { /* clk_div doesn't support odd number */ - chip->clk_div = (dws->max_freq / transfer->speed_hz + 1) & 0xfffe; + chip->clk_div = (DIV_ROUND_UP(dws->max_freq, transfer->speed_hz) + 1) & 0xfffe; chip->speed_hz = transfer->speed_hz; } dws->current_freq = transfer->speed_hz; -- 2.7.4 -- To unsubscribe from this list: send the line "unsubscribe linux-spi" in the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org More majordomo info at http://vger.kernel.org/majordomo-info.html ^ permalink raw reply related [flat|nested] 6+ messages in thread
* Applied "spi: dw: round up result of calculation for clock divider" to the spi tree 2016-09-06 17:16 ` [PATCH v3 " Matthias Seidel 2016-09-06 22:21 ` Mark Brown @ 2016-09-12 19:08 ` Mark Brown 1 sibling, 0 replies; 6+ messages in thread From: Mark Brown @ 2016-09-12 19:08 UTC (permalink / raw) To: Matthias Seidel; +Cc: Mark Brown, Mark Brown, linux-spi-u79uwXL29TY76Z2rM5mHXA The patch spi: dw: round up result of calculation for clock divider has been applied to the spi tree at git://git.kernel.org/pub/scm/linux/kernel/git/broonie/spi.git All being well this means that it will be integrated into the linux-next tree (usually sometime in the next 24 hours) and sent to Linus during the next merge window (or sooner if it is a bug fix), however if problems are discovered then the patch may be dropped or reverted. You may get further e-mails resulting from automated or manual testing and review of the tree, please engage with people reporting problems and send followup patches addressing any issues that are reported if needed. If any updates are required or you are submitting further changes they should be sent as incremental updates against current git, existing patches will not be replaced. Please add any relevant lists and maintainers to the CCs when replying to this mail. Thanks, Mark >From 3aef463222eaf1ca505629e93a0b64e4040a4472 Mon Sep 17 00:00:00 2001 From: Matthias Seidel <kernel-NoMTM8u0nx3R7s880joybQ@public.gmane.org> Date: Wed, 7 Sep 2016 17:45:30 +0200 Subject: [PATCH] spi: dw: round up result of calculation for clock divider Avoid ending up with a higher frequency than requested Signed-off-by: Matthias Seidel <kernel-NoMTM8u0nx3R7s880joybQ@public.gmane.org> Signed-off-by: Mark Brown <broonie-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org> --- drivers/spi/spi-dw.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/spi/spi-dw.c b/drivers/spi/spi-dw.c index c85e4b327a4a..27960e46135d 100644 --- a/drivers/spi/spi-dw.c +++ b/drivers/spi/spi-dw.c @@ -300,7 +300,7 @@ static int dw_spi_transfer_one(struct spi_master *master, if (transfer->speed_hz != dws->current_freq) { if (transfer->speed_hz != chip->speed_hz) { /* clk_div doesn't support odd number */ - chip->clk_div = (dws->max_freq / transfer->speed_hz + 1) & 0xfffe; + chip->clk_div = (DIV_ROUND_UP(dws->max_freq, transfer->speed_hz) + 1) & 0xfffe; chip->speed_hz = transfer->speed_hz; } dws->current_freq = transfer->speed_hz; -- 2.8.1 -- To unsubscribe from this list: send the line "unsubscribe linux-spi" in the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org More majordomo info at http://vger.kernel.org/majordomo-info.html ^ permalink raw reply related [flat|nested] 6+ messages in thread
end of thread, other threads:[~2016-09-12 19:08 UTC | newest]
Thread overview: 6+ messages (download: mbox.gz follow: Atom feed
-- links below jump to the message on this page --
2016-09-04 0:05 [PATCH v2 2/2] spi: dw: round up result of calculation for clock divider Matthias Seidel
2016-09-06 10:53 ` Mark Brown
[not found] ` <20160906105352.GK3950-GFdadSzt00ze9xe1eoZjHA@public.gmane.org>
2016-09-06 17:16 ` [PATCH v3 " Matthias Seidel
2016-09-06 22:21 ` Mark Brown
[not found] ` <20160906222131.GT3950-GFdadSzt00ze9xe1eoZjHA@public.gmane.org>
2016-09-07 15:45 ` [PATCH v4] " Matthias Seidel
2016-09-12 19:08 ` Applied "spi: dw: round up result of calculation for clock divider" to the spi tree Mark Brown
This is a public inbox, see mirroring instructions for how to clone and mirror all data and code used for this inbox; as well as URLs for NNTP newsgroup(s).