Re: [PATCH v2 2/2] media: rc: add driver for IR remote receiver on MT7623 SoC

Sean Young
2017-01-10T17:23:56Z

Hi Sean,

The driver is looking very good, we are looking at minor details now.

On Tue, Jan 10, 2017 at 09:59:49PM +0800, Sean Wang wrote:
> On Tue, 2017-01-10 at 11:09 +0000, Sean Young wrote:
>
> > > +#include <linux/clk.h>
> > > +#include <linux/interrupt.h>
> > > +#include <linux/module.h>
> > > +#include <linux/of_platform.h>
> > > +#include <linux/reset.h>
> > > +#include <media/rc-core.h>
> > > +
> > > +#define MTK_IR_DEV KBUILD_MODNAME
> >
> > You could remove this #define and just use KBUILD_MODNAME
>
> I preferred to use MTK_IR_DEV internally that helps
> renaming in the future if necessary.

ok.

> >
> > > +
> > > +/* Register to enable PWM and IR */
> > > +#define MTK_CONFIG_HIGH_REG 0x0c
> > > +/* Enable IR pulse width detection */
> > > +#define MTK_PWM_EN BIT(13)
> > > +/* Enable IR hardware function */
> > > +#define MTK_IR_EN BIT(0)
> > > +
> > > +/* Register to setting sample period */
> > > +#define MTK_CONFIG_LOW_REG 0x10
> > > +/* Field to set sample period */
> > > +#define CHK_PERIOD DIV_ROUND_CLOSEST(MTK_IR_SAMPLE, \
> > > + MTK_IR_CLK_PERIOD)
> > > +#define MTK_CHK_PERIOD (((CHK_PERIOD) << 8) & (GENMASK(20, 8)))
> > > +#define MTK_CHK_PERIOD_MASK (GENMASK(20, 8))
> > > +
> > > +/* Register to clear state of state machine */
> > > +#define MTK_IRCLR_REG 0x20
> > > +/* Bit to restart IR receiving */
> > > +#define MTK_IRCLR BIT(0)
> > > +
> > > +/* Register containing pulse width data */
> > > +#define MTK_CHKDATA_REG(i) (0x88 + 4 * (i))
> > > +#define MTK_WIDTH_MASK (GENMASK(7, 0))
> > > +
> > > +/* Register to enable IR interrupt */
> > > +#define MTK_IRINT_EN_REG 0xcc
> > > +/* Bit to enable interrupt */
> > > +#define MTK_IRINT_EN BIT(0)
> > > +
> > > +/* Register to ack IR interrupt */
> > > +#define MTK_IRINT_CLR_REG 0xd0
> > > +/* Bit to clear interrupt status */
> > > +#define MTK_IRINT_CLR BIT(0)
> > > +
> > > +/* Maximum count of samples */
> > > +#define MTK_MAX_SAMPLES 0xff
> > > +/* Indicate the end of IR message */
> > > +#define MTK_IR_END(v, p) ((v) == MTK_MAX_SAMPLES && (p) == 0)
> > > +/* Number of registers to record the pulse width */
> > > +#define MTK_CHKDATA_SZ 17
> > > +/* Source clock frequency */
> > > +#define MTK_IR_BASE_CLK 273000000
> > > +/* Frequency after IR internal divider */
> > > +#define MTK_IR_CLK_FREQ (MTK_IR_BASE_CLK / 4)
>
> > > +static irqreturn_t mtk_ir_irq(int irqno, void *dev_id)
> > > +{
> > > + struct mtk_ir *ir = dev_id;
> > > + u8 wid = 0;
> > > + u32 i, j, val;
> > > + DEFINE_IR_RAW_EVENT(rawir);
> > > +
> > > + mtk_irq_disable(ir, MTK_IRINT_EN);
> >
> > The kernel guarantees that calls to the interrupt handler are serialised,
> > no need to disable the interrupt in the handler.
>
> agreed. I will save the mtk irq disable/enable and retest again.
>
>
> > > +
> > > + /* Reset decoder state machine */
> > > + ir_raw_event_reset(ir->rc);
> >
> > Not needed.
>
>
> two reasons I added the line here
>
> 1)
> I thought it is possible the decoder goes to the
> middle state when getting the data not belonged
> to the protocol. If so, that would cause the decoding
> fails in the next time receiving the valid protocol data.

The last IR event submitted will always be a long space, that's enough
to reset the decoders. Adding a ir_raw_event_reset() will do this
more explicitly, rather than their state machines resetting themselves
through the trailing space.

> 2)
> the mtk hardware register always contains the start of
> IR message. So force to sync the state between
> HW and ir-core.
>
>
>
> > > +
> > > + /* First message must be pulse */
> > > + rawir.pulse = false;
> >
> > pulse = true?
>
> becasue of rawir.pulse = !rawir.pulse does as below
> so the initial value is set as false.

Ah, sorry, of course. :)

> > > +
> > > + /* Handle all pulse and space IR controller captures */
> > > + for (i = 0 ; i < MTK_CHKDATA_SZ ; i++) {
> > > + val = mtk_r32(ir, MTK_CHKDATA_REG(i));
> > > + dev_dbg(ir->dev, "@reg%d=0x%08x\n", i, val);
> > > +
> > > + for (j = 0 ; j < 4 ; j++) {
> > > + wid = (val & (MTK_WIDTH_MASK << j * 8)) >> j * 8;
> > > + rawir.pulse = !rawir.pulse;
> > > + rawir.duration = wid * (MTK_IR_SAMPLE + 1);
> > > + ir_raw_event_store_with_filter(ir->rc, &rawir);
> > > + }
> >
> > In v1 you would break out of the loop if the ir message was shorter, but
> > now you are always passing on 68 pulses and spaces. Is that right?
>
> as I asked in the previous mail list as below i copied from it, so i
> made some changes ...
>
> """""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""
> > I had another question. I found multiple and same IR messages being
> > received when using SONY remote controller. Should driver needs to
> > report each message or only one of these to the upper layer ?
>
> In general the driver shouldn't try to change any IR message, this
> should be done in rc-core if necessary.
>
> rc-core should handle this correctly. If the same key is received twice
> within IR_KEYPRESS_TIMEOUT (250ms) then it not reported to the input
> layer.
> """"""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""
>
> for example:
> the 68 pulse/spaces might contains 2.x IR messages when I
> pressed one key on SONY remote control.
>
> the v1 proposed is passing only one IR message into ir-core ;
> the v2 done is passing all IR messages even including the last
> incomplete message into ir-core.

Yes, agreed. Sorry if I wasn't clear. I just wanted to make sure you've
thought about what happens when the IR message is short (e.g. rc-5 with
23 pulse-spaces). Are the remaining registers 0 or do we get stale data
from a previous transmit?

> But I was still afraid the state machine can't go back to initial state
> after receiving these incomplete data.
>
> So the ir_raw_event_reset() call in the beginning of ISR seems becoming
> more important.
>
> > > + }
> > > +
> > > + /* The maximum number of edges the IR controller can
> > > + * hold is MTK_CHKDATA_SZ * 4. So if received IR messages
> > > + * is over the limit, the last incomplete IR message would
> > > + * be appended trailing space and still would be sent into
> > > + * ir-rc-raw to decode. That helps it is possible that it
> > > + * has enough information to decode a scancode even if the
> > > + * trailing end of the message is missing.
> > > + */
> > > + if (!MTK_IR_END(wid, rawir.pulse)) {
> > > + rawir.pulse = false;
> > > + rawir.duration = MTK_MAX_SAMPLES * (MTK_IR_SAMPLE + 1);
> > > + ir_raw_event_store_with_filter(ir->rc, &rawir);
> > > + }

See here you add a long space if one was not added already.

> > > +
> > > + ir_raw_event_handle(ir->rc);
> > > +
> > > + /* Restart controller for the next receive */
> > > + mtk_w32_mask(ir, 0x1, MTK_IRCLR, MTK_IRCLR_REG);
> > > +
> > > + /* Clear interrupt status */
> > > + mtk_w32_mask(ir, 0x1, MTK_IRINT_CLR, MTK_IRINT_CLR_REG);
> > > +
> > > + /* Enable interrupt */
> > > + mtk_irq_enable(ir, MTK_IRINT_EN);
> > > +
> > > + return IRQ_HANDLED;
> > > +}
> > > +
> > > +static int mtk_ir_probe(struct platform_device *pdev)
> > > +{
> > > + struct device *dev = &pdev->dev;
> > > + struct device_node *dn = dev->of_node;
> > > + struct resource *res;
> > > + struct mtk_ir *ir;
> > > + u32 val;
> > > + int ret = 0;
> > > + const char *map_name;
> > > +
> > > + ir = devm_kzalloc(dev, sizeof(struct mtk_ir), GFP_KERNEL);
> > > + if (!ir)
> > > + return -ENOMEM;
> > > +
> > > + ir->dev = dev;
> > > +
> > > + if (!of_device_is_compatible(dn, "mediatek,mt7623-cir"))
> > > + return -ENODEV;
> > > +
> > > + ir->clk = devm_clk_get(dev, "clk");
> > > + if (IS_ERR(ir->clk)) {
> > > + dev_err(dev, "failed to get a ir clock.\n");
> > > + return PTR_ERR(ir->clk);
> > > + }
> > > +
> > > + res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> > > + ir->base = devm_ioremap_resource(dev, res);
> > > + if (IS_ERR(ir->base)) {
> > > + dev_err(dev, "failed to map registers\n");
> > > + return PTR_ERR(ir->base);
> > > + }
> > > +
> > > + ir->rc = devm_rc_allocate_device(dev, RC_DRIVER_IR_RAW);
> > > + if (!ir->rc) {
> > > + dev_err(dev, "failed to allocate device\n");
> > > + return -ENOMEM;
> > > + }
> > > +
> > > + ir->rc->priv = ir;
> > > + ir->rc->input_name = MTK_IR_DEV;
> > > + ir->rc->input_phys = MTK_IR_DEV "/input0";
> > > + ir->rc->input_id.bustype = BUS_HOST;
> > > + ir->rc->input_id.vendor = 0x0001;
> > > + ir->rc->input_id.product = 0x0001;
> > > + ir->rc->input_id.version = 0x0001;
> > > + map_name = of_get_property(dn, "linux,rc-map-name", NULL);
> > > + ir->rc->map_name = map_name ?: RC_MAP_EMPTY;
> > > + ir->rc->dev.parent = dev;
> > > + ir->rc->driver_name = MTK_IR_DEV;
> > > + ir->rc->allowed_protocols = RC_BIT_ALL;
> > > + ir->rc->rx_resolution = MTK_IR_SAMPLE;
> > > + ir->rc->timeout = MTK_MAX_SAMPLES * (MTK_IR_SAMPLE + 1);
> > > +
> > > + ret = devm_rc_register_device(dev, ir->rc);
> >
> > Here you do devm_rc_register_device()
>
> does it have problem ?

Sorry, no. I just wanted to highlight wrt a comment below.
>
>
> > > + if (ret) {
> > > + dev_err(dev, "failed to register rc device\n");
> > > + return ret;
> > > + }
> > > +
> > > + platform_set_drvdata(pdev, ir);
> > > +
> > > + ir->irq = platform_get_irq(pdev, 0);
> > > + if (ir->irq < 0) {
> > > + dev_err(dev, "no irq resource\n");
> > > + return -ENODEV;
> > > + }
> > > +
> > > + /* Enable interrupt after proper hardware
> > > + * setup and IRQ handler registration
> > > + */
> > > + if (clk_prepare_enable(ir->clk)) {
> > > + dev_err(dev, "try to enable ir_clk failed\n");
> > > + ret = -EINVAL;
> > > + goto exit_clkdisable_clk;
> > > + }
> > > +
> > > + mtk_irq_disable(ir, MTK_IRINT_EN);
> > > +
> > > + ret = devm_request_irq(dev, ir->irq, mtk_ir_irq, 0, MTK_IR_DEV, ir);
> > > + if (ret) {
> > > + dev_err(dev, "failed request irq\n");
> > > + goto exit_clkdisable_clk;
> > > + }
> > > +
> > > + /* Enable IR and PWM */
> > > + val = mtk_r32(ir, MTK_CONFIG_HIGH_REG);
> > > + val |= MTK_PWM_EN | MTK_IR_EN;
> > > + mtk_w32(ir, val, MTK_CONFIG_HIGH_REG);
> > > +
> > > + /* Setting sample period */
> > > + mtk_w32_mask(ir, MTK_CHK_PERIOD, MTK_CHK_PERIOD_MASK,
> > > + MTK_CONFIG_LOW_REG);
> > > +
> > > + mtk_irq_enable(ir, MTK_IRINT_EN);
> > > +
> > > + dev_info(dev, "Initialized MT7623 IR driver, sample period = %luus\n",
> > > + DIV_ROUND_CLOSEST(MTK_IR_SAMPLE, 1000));
> > > +
> > > + return 0;
> > > +
> > > +exit_clkdisable_clk:
> > > + clk_disable_unprepare(ir->clk);
> > > +
> > > + return ret;
> > > +}
> > > +
> > > +static int mtk_ir_remove(struct platform_device *pdev)
> > > +{
> > > + struct mtk_ir *ir = platform_get_drvdata(pdev);
> > > +
> > > + /* Avoid contention between remove handler and
> > > + * IRQ handler so that disabling IR interrupt and
> > > + * waiting for pending IRQ handler to complete
> > > + */
> > > + mtk_irq_disable(ir, MTK_IRINT_EN);
> > > + synchronize_irq(ir->irq);
> > > +
> > > + clk_disable_unprepare(ir->clk);
> > > +
> > > + rc_unregister_device(ir->rc);
> >
> > Yet here you explicitly call rc_unregister_device(). Since it was registered
> > with the devm call, this call is not needed and will lead to double frees etc
>
> bug :( . I will fix it ..
>
> > > +
> > > + return 0;
> > > +}
> > > +
> > > +static const struct of_device_id mtk_ir_match[] = {
> > > + { .compatible = "mediatek,mt7623-cir" },
> > > + {},
> > > +};
> > > +MODULE_DEVICE_TABLE(of, mtk_ir_match);
> > > +
> > > +static struct platform_driver mtk_ir_driver = {
> > > + .probe = mtk_ir_probe,
> > > + .remove = mtk_ir_remove,
> > > + .driver = {
> > > + .name = MTK_IR_DEV,
> > > + .of_match_table = mtk_ir_match,
> > > + },
> > > +};
> > > +
> > > +module_platform_driver(mtk_ir_driver);
> > > +
> > > +MODULE_DESCRIPTION("Mediatek IR Receiver Controller Driver");
> > > +MODULE_AUTHOR("Sean Wang <sean.wang-NuS5LvNUpcJWk0Htik3J/w@public.gmane.org>");
> > > +MODULE_LICENSE("GPL");
> > > --
> > > 2.7.4
> > >
>
>
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