From mboxrd@z Thu Jan 1 00:00:00 1970 From: Matthias Seidel Subject: [PATCH v2 1/2] spi: dw: fix multiple slaves with different baudrates Date: Sun, 4 Sep 2016 02:04:49 +0200 Message-ID: <20160904020449.217e13f4@vm> References: <84f71116-1c79-6769-d537-860ac6ea0de9@mseidel.net> <20160903110118.GT3950@sirena.org.uk> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Cc: linux-spi-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Mark Brown Return-path: In-Reply-To: <20160903110118.GT3950-GFdadSzt00ze9xe1eoZjHA@public.gmane.org> Sender: linux-spi-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org List-ID: Add current master clock to dws struct and compare it against the requestedtransfer speed. Update clock divider only if necessary. Signed-off-by: Matthias Seidel --- v2 First time for me, Thunderbird messed up the tabs, sorry. --- The current implementation stores the transfer speed in the chip struct. If there are multiple slaves which need different clock speeds, the clk_div only gets updated the first time for each slave as speed_hz is 0. After that the comparison always shows the transfer-speed to be equal to the chipspeed and the divider is not updated. --- drivers/spi/spi-dw.c | 15 +++++++-------- drivers/spi/spi-dw.h | 1 + 2 files changed, 8 insertions(+), 8 deletions(-) diff --git a/drivers/spi/spi-dw.c b/drivers/spi/spi-dw.c index c09bb74..c85e4b3 100644 --- a/drivers/spi/spi-dw.c +++ b/drivers/spi/spi-dw.c @@ -283,7 +283,6 @@ static int dw_spi_transfer_one(struct spi_master *master, struct chip_data *chip = spi_get_ctldata(spi); u8 imask = 0; u16 txlevel = 0; - u16 clk_div; u32 cr0; int ret; @@ -298,13 +297,13 @@ static int dw_spi_transfer_one(struct spi_master *master, spi_enable_chip(dws, 0); /* Handle per transfer options for bpw and speed */ - if (transfer->speed_hz != chip->speed_hz) { - /* clk_div doesn't support odd number */ - clk_div = (dws->max_freq / transfer->speed_hz + 1) & 0xfffe; - - chip->speed_hz = transfer->speed_hz; - chip->clk_div = clk_div; - + 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->speed_hz = transfer->speed_hz; + } + dws->current_freq = transfer->speed_hz; spi_set_clk(dws, chip->clk_div); } if (transfer->bits_per_word == 8) { diff --git a/drivers/spi/spi-dw.h b/drivers/spi/spi-dw.h index 61bc3cb..c21ca02 100644 --- a/drivers/spi/spi-dw.h +++ b/drivers/spi/spi-dw.h @@ -123,6 +123,7 @@ struct dw_spi { u8 n_bytes; /* current is a 1/2 bytes op */ u32 dma_width; irqreturn_t (*transfer_handler)(struct dw_spi *dws); + u32 current_freq; /* frequency in hz */ /* DMA info */ int dma_inited; -- 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