| Message ID | 1439289789-29026-1-git-send-email-leilk.liu@mediatek.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
Hi, On Tue, Aug 11, 2015 at 12:43 PM, Leilk Liu <leilk.liu@mediatek.com> wrote: > This patch fixes endian warnings detected by sparse: > - sparse: incorrect type in argument 1 (different base types) > expected unsigned int [unsigned] val > got restricted __le32 [usertype] <noident> > - sparse: incorrect type in argument 1 (different base types) > expected unsigned int [unsigned] val > got restricted __le32 [usertype] <noident> This doesn't "fix" the warning, it only hides the warning and leaves the actual issue unfixed. > > Signed-off-by: Leilk Liu <leilk.liu@mediatek.com> > --- > drivers/spi/spi-mt65xx.c | 6 ++++-- > 1 file changed, 4 insertions(+), 2 deletions(-) > > diff --git a/drivers/spi/spi-mt65xx.c b/drivers/spi/spi-mt65xx.c > index 4676b01..ae645fa 100644 > --- a/drivers/spi/spi-mt65xx.c > +++ b/drivers/spi/spi-mt65xx.c > @@ -359,9 +359,11 @@ static void mtk_spi_setup_dma_addr(struct spi_master *master, > struct mtk_spi *mdata = spi_master_get_devdata(master); > > if (mdata->tx_sgl) > - writel(cpu_to_le32(xfer->tx_dma), mdata->base + SPI_TX_SRC_REG); > + writel((__force u32)cpu_to_le32(xfer->tx_dma), > + mdata->base + SPI_TX_SRC_REG); > if (mdata->rx_sgl) > - writel(cpu_to_le32(xfer->rx_dma), mdata->base + SPI_RX_DST_REG); > + writel((__force u32)cpu_to_le32(xfer->rx_dma), > + mdata->base + SPI_RX_DST_REG); The issue here is that writel already does a cpu_to_le32 conversion, so the extra cpu_to_le32 calls are actually bogus and need to be removed. Else it will do a double conversion on big endian systems, resulting in the data being written in big endian. Jonas
Hello Mark, This patch is applied, should I append a new patch or you rollback it? Thanks. On Wed, 2015-08-12 at 16:45 +0200, Jonas Gorski wrote: > Hi, > > On Tue, Aug 11, 2015 at 12:43 PM, Leilk Liu <leilk.liu@mediatek.com> wrote: > > This patch fixes endian warnings detected by sparse: > > - sparse: incorrect type in argument 1 (different base types) > > expected unsigned int [unsigned] val > > got restricted __le32 [usertype] <noident> > > - sparse: incorrect type in argument 1 (different base types) > > expected unsigned int [unsigned] val > > got restricted __le32 [usertype] <noident> > > This doesn't "fix" the warning, it only hides the warning and leaves > the actual issue unfixed. > > > > > Signed-off-by: Leilk Liu <leilk.liu@mediatek.com> > > --- > > drivers/spi/spi-mt65xx.c | 6 ++++-- > > 1 file changed, 4 insertions(+), 2 deletions(-) > > > > diff --git a/drivers/spi/spi-mt65xx.c b/drivers/spi/spi-mt65xx.c > > index 4676b01..ae645fa 100644 > > --- a/drivers/spi/spi-mt65xx.c > > +++ b/drivers/spi/spi-mt65xx.c > > @@ -359,9 +359,11 @@ static void mtk_spi_setup_dma_addr(struct spi_master *master, > > struct mtk_spi *mdata = spi_master_get_devdata(master); > > > > if (mdata->tx_sgl) > > - writel(cpu_to_le32(xfer->tx_dma), mdata->base + SPI_TX_SRC_REG); > > + writel((__force u32)cpu_to_le32(xfer->tx_dma), > > + mdata->base + SPI_TX_SRC_REG); > > if (mdata->rx_sgl) > > - writel(cpu_to_le32(xfer->rx_dma), mdata->base + SPI_RX_DST_REG); > > + writel((__force u32)cpu_to_le32(xfer->rx_dma), > > + mdata->base + SPI_RX_DST_REG); > > The issue here is that writel already does a cpu_to_le32 conversion, > so the extra cpu_to_le32 calls are actually bogus and need to be > removed. Else it will do a double conversion on big endian systems, > resulting in the data being written in big endian. > > > Jonas
On Thu, Aug 13, 2015 at 10:11:59AM +0800, lei liu wrote: > This patch is applied, should I append a new patch or you rollback it? > Thanks. Please send an incremental patch on top of what's applied and don't top post.
On Tuesday 11 August 2015 18:43:09 Leilk Liu wrote: > @@ -359,9 +359,11 @@ static void mtk_spi_setup_dma_addr(struct spi_master *master, > struct mtk_spi *mdata = spi_master_get_devdata(master); > > if (mdata->tx_sgl) > - writel(cpu_to_le32(xfer->tx_dma), mdata->base + SPI_TX_SRC_REG); > + writel((__force u32)cpu_to_le32(xfer->tx_dma), > + mdata->base + SPI_TX_SRC_REG); > if (mdata->rx_sgl) > - writel(cpu_to_le32(xfer->rx_dma), mdata->base + SPI_RX_DST_REG); > + writel((__force u32)cpu_to_le32(xfer->rx_dma), > + mdata->base + SPI_RX_DST_REG); > } > This looks wrong: writel takes a CPU-endian argument, so the value returned from cpu_to_le32() is not appropriate. The warning is correct, and you have to remove the cpu_to_le32() conversion in order to get the driver to behave correctly when the kernel is built as big-endian. Arnd
On Saturday 15 August 2015 22:16:03 Arnd Bergmann wrote: > On Tuesday 11 August 2015 18:43:09 Leilk Liu wrote: > > @@ -359,9 +359,11 @@ static void mtk_spi_setup_dma_addr(struct spi_master *master, > > struct mtk_spi *mdata = spi_master_get_devdata(master); > > > > if (mdata->tx_sgl) > > - writel(cpu_to_le32(xfer->tx_dma), mdata->base + SPI_TX_SRC_REG); > > + writel((__force u32)cpu_to_le32(xfer->tx_dma), > > + mdata->base + SPI_TX_SRC_REG); > > if (mdata->rx_sgl) > > - writel(cpu_to_le32(xfer->rx_dma), mdata->base + SPI_RX_DST_REG); > > + writel((__force u32)cpu_to_le32(xfer->rx_dma), > > + mdata->base + SPI_RX_DST_REG); > > } > > > > This looks wrong: writel takes a CPU-endian argument, so the value returned > from cpu_to_le32() is not appropriate. > > The warning is correct, and you have to remove the cpu_to_le32() conversion > in order to get the driver to behave correctly when the kernel is built > as big-endian. Nevermind, I now saw the issue has already been raised. Arnd
On Sat, Aug 15, 2015 at 10:16:03PM +0200, Arnd Bergmann wrote: > On Tuesday 11 August 2015 18:43:09 Leilk Liu wrote: > > @@ -359,9 +359,11 @@ static void mtk_spi_setup_dma_addr(struct spi_master *master, > > struct mtk_spi *mdata = spi_master_get_devdata(master); > > > > if (mdata->tx_sgl) > > - writel(cpu_to_le32(xfer->tx_dma), mdata->base + SPI_TX_SRC_REG); > > + writel((__force u32)cpu_to_le32(xfer->tx_dma), > > + mdata->base + SPI_TX_SRC_REG); > > if (mdata->rx_sgl) > > - writel(cpu_to_le32(xfer->rx_dma), mdata->base + SPI_RX_DST_REG); > > + writel((__force u32)cpu_to_le32(xfer->rx_dma), > > + mdata->base + SPI_RX_DST_REG); > > } > > > > This looks wrong: writel takes a CPU-endian argument, so the value returned > from cpu_to_le32() is not appropriate. > > The warning is correct, and you have to remove the cpu_to_le32() conversion > in order to get the driver to behave correctly when the kernel is built > as big-endian. Indeed, it's about time people started thinking more about the warnings and why we have coded things in the way we have. Look people. cpu_to_le32() takes a value in the CPU endian, and converts it to a little endian 32-bit number. See, the clue is in the name. All writel() implementations take a CPU number and write it in little endian format. Hence, writel() almost always uses cpu_to_le32() internally. Now think about what you're saying with "cpu_to_le32(cpu_to_le32())". It's utter rubbish, total crap. It's wrong no matter which way you look at it. We have le32_to_cpu() which does what it says on the tin. Same with be32_to_cpu() and cpu_to_be32(). Don't hack around this stuff with __force. If you're having to use __force to get rid of a warning here, you _ARE_ doing something wrong, no questions about that. __force in driver code is a definite sign that you are doing something wrong. Don't do it. Ask the question if you think you need it.
On Sun, Aug 16, 2015 at 03:06:39PM +0100, Russell King - ARM Linux wrote: > All writel() implementations take a CPU number and write it in little > endian format. Hence, writel() almost always uses cpu_to_le32() > internally. I think the reason this keeps coming up is that people aren't expecting writel() to be doing endianness conversion, it's easy to get caught out by it.
diff --git a/drivers/spi/spi-mt65xx.c b/drivers/spi/spi-mt65xx.c index 4676b01..ae645fa 100644 --- a/drivers/spi/spi-mt65xx.c +++ b/drivers/spi/spi-mt65xx.c @@ -359,9 +359,11 @@ static void mtk_spi_setup_dma_addr(struct spi_master *master, struct mtk_spi *mdata = spi_master_get_devdata(master); if (mdata->tx_sgl) - writel(cpu_to_le32(xfer->tx_dma), mdata->base + SPI_TX_SRC_REG); + writel((__force u32)cpu_to_le32(xfer->tx_dma), + mdata->base + SPI_TX_SRC_REG); if (mdata->rx_sgl) - writel(cpu_to_le32(xfer->rx_dma), mdata->base + SPI_RX_DST_REG); + writel((__force u32)cpu_to_le32(xfer->rx_dma), + mdata->base + SPI_RX_DST_REG); } static int mtk_spi_fifo_transfer(struct spi_master *master,
This patch fixes endian warnings detected by sparse: - sparse: incorrect type in argument 1 (different base types) expected unsigned int [unsigned] val got restricted __le32 [usertype] <noident> - sparse: incorrect type in argument 1 (different base types) expected unsigned int [unsigned] val got restricted __le32 [usertype] <noident> Signed-off-by: Leilk Liu <leilk.liu@mediatek.com> --- drivers/spi/spi-mt65xx.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-)