Re: [PATCH v5 3/5] i2c: mediatek: Add arb clock in i2c driver

Nicolas Boichat
2019-03-06T10:49:26Z

One thing I missed from Matthias' comment on v4:
https://patchwork.kernel.org/patch/10822083/

On Wed, Mar 6, 2019 at 6:44 PM Nicolas Boichat <drinkcat@chromium.org> wrote:
>
> On Tue, Feb 26, 2019 at 9:11 PM Qii Wang <qii.wang@mediatek.com> wrote:
> >
> > When two i2c controllers are internally connected to the same
> > GPIO pins, the arb clock is needed to ensure that the waveforms
> > do not interfere with each other.
> >
> > Signed-off-by: Qii Wang <qii.wang@mediatek.com>
>
> Reviewed-by: Nicolas Boichat <drinkcat@chromium.org>
>
> > ---
> > drivers/i2c/busses/i2c-mt65xx.c | 25 ++++++++++++++++++++++---
> > 1 file changed, 22 insertions(+), 3 deletions(-)
> >
> > diff --git a/drivers/i2c/busses/i2c-mt65xx.c b/drivers/i2c/busses/i2c-mt65xx.c
> > index 428ac99..14d6b38 100644
> > --- a/drivers/i2c/busses/i2c-mt65xx.c
> > +++ b/drivers/i2c/busses/i2c-mt65xx.c
> > @@ -35,6 +35,7 @@
> > #include <linux/slab.h>
> >
> > #define I2C_RS_TRANSFER (1 << 4)
> > +#define I2C_ARB_LOST (1 << 3)
> > #define I2C_HS_NACKERR (1 << 2)
> > #define I2C_ACKERR (1 << 1)
> > #define I2C_TRANSAC_COMP (1 << 0)
> > @@ -181,6 +182,7 @@ struct mtk_i2c {
> > struct clk *clk_main; /* main clock for i2c bus */
> > struct clk *clk_dma; /* DMA clock for i2c via DMA */
> > struct clk *clk_pmic; /* PMIC clock for i2c from PMIC */
> > + struct clk *clk_arb; /* Arbitrator clock for i2c */
> > bool have_pmic; /* can use i2c pins from PMIC */
> > bool use_push_pull; /* IO config push-pull mode */
> >
> > @@ -299,8 +301,18 @@ static int mtk_i2c_clock_enable(struct mtk_i2c *i2c)
> > if (ret)
> > goto err_pmic;
> > }
> > +
> > + if (i2c->clk_arb) {
> > + ret = clk_prepare_enable(i2c->clk_arb);
> > + if (ret)
> > + goto err_arb;
> > + }
> > +
> > return 0;
> >
> > +err_arb:
> > + if (i2c->have_pmic)
> > + clk_disable_unprepare(i2c->clk_pmic);
> > err_pmic:
> > clk_disable_unprepare(i2c->clk_main);
> > err_main:
> > @@ -311,6 +323,9 @@ static int mtk_i2c_clock_enable(struct mtk_i2c *i2c)
> >
> > static void mtk_i2c_clock_disable(struct mtk_i2c *i2c)
> > {
> > + if (i2c->clk_arb)
> > + clk_disable_unprepare(i2c->clk_arb);
> > +
> > if (i2c->have_pmic)
> > clk_disable_unprepare(i2c->clk_pmic);
> >
> > @@ -519,13 +534,13 @@ static int mtk_i2c_do_transfer(struct mtk_i2c *i2c, struct i2c_msg *msgs,
> >
> > /* Clear interrupt status */
> > mtk_i2c_writew(i2c, restart_flag | I2C_HS_NACKERR | I2C_ACKERR |
> > - I2C_TRANSAC_COMP, OFFSET_INTR_STAT);
> > + I2C_ARB_LOST | I2C_TRANSAC_COMP, OFFSET_INTR_STAT);

Is it ok to set I2C_ARB_LOST on _all_ SoC that this driver supports?
If so, please at least say so in the commit message.

> >
> > mtk_i2c_writew(i2c, I2C_FIFO_ADDR_CLR, OFFSET_FIFO_ADDR_CLR);
> >
> > /* Enable interrupt */
> > mtk_i2c_writew(i2c, restart_flag | I2C_HS_NACKERR | I2C_ACKERR |
> > - I2C_TRANSAC_COMP, OFFSET_INTR_MASK);
> > + I2C_ARB_LOST | I2C_TRANSAC_COMP, OFFSET_INTR_MASK);
> >
> > /* Set transfer and transaction len */
> > if (i2c->op == I2C_MASTER_WRRD) {
> > @@ -659,7 +674,7 @@ static int mtk_i2c_do_transfer(struct mtk_i2c *i2c, struct i2c_msg *msgs,
> >
> > /* Clear interrupt mask */
> > mtk_i2c_writew(i2c, ~(restart_flag | I2C_HS_NACKERR | I2C_ACKERR |
> > - I2C_TRANSAC_COMP), OFFSET_INTR_MASK);
> > + I2C_ARB_LOST | I2C_TRANSAC_COMP), OFFSET_INTR_MASK);
> >
> > if (i2c->op == I2C_MASTER_WR) {
> > dma_unmap_single(i2c->dev, wpaddr,
> > @@ -884,6 +899,10 @@ static int mtk_i2c_probe(struct platform_device *pdev)
> > return PTR_ERR(i2c->clk_dma);
> > }
> >
> > + i2c->clk_arb = devm_clk_get(&pdev->dev, "arb");
> > + if (IS_ERR(i2c->clk_arb))
> > + i2c->clk_arb = NULL;
> > +
> > clk = i2c->clk_main;
> > if (i2c->have_pmic) {
> > i2c->clk_pmic = devm_clk_get(&pdev->dev, "pmic");
> > --
> > 1.7.9.5
> >