Re: [PATCH v3] rpmsg: qcom_smd: Access APCS through mailbox framework

Frank Rowand
2018-08-31T20:41:21Z

On 08/30/18 21:07, Bjorn Andersson wrote:
> On Thu 30 Aug 20:57 PDT 2018, Frank Rowand wrote:
>
>> Hi Bjorn,
>>
>>
>> On 04/19/18 18:17, Bjorn Andersson wrote:
>>> Attempt to acquire the APCS IPC through the mailbox framework and fall
>>> back to the old syscon based approach, to allow us to move away from
>>> using the syscon.
>>>
>>> Reviewed-by: Arun Kumar Neelakantam <aneela@codeaurora.org>
>>> Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>
>>> ---
>>>
>>> Changes since v2:
>>> - Added comment about mbox_send_message() return value.
>>>
>>> .../devicetree/bindings/soc/qcom/qcom,smd.txt | 8 ++-
>>> drivers/rpmsg/Kconfig | 1 +
>>> drivers/rpmsg/qcom_smd.c | 67 ++++++++++++++++------
>>> 3 files changed, 56 insertions(+), 20 deletions(-)
>>
>> This patch in the mainline Linux kernel as commit ab460a2e72dabecfdabd45eb7e3ee2d73fc876d4
>> causes a problem with the APQ8074 Dragonboard. The mmc device is not set up
>> with the patch applied, thus I do not have the block device my root file system
>> is located on.
>>
>> Testing on v4.18, if I revert this commit the mmc device is available.
>>
>> I'll reply to this email with the console messages for 4.18 and for 4.18 with
>> this commit reverted.
>>
>
> The mmc device would fail to come up if the regulators didn't come up,
> which would be the result of smd not working. But it should fallback to
> the old mechanism if no mailbox is specified.
>
> Can you double check that CONFIG_RPMSG_QCOM_SMD is still set in your
> .config after applying and building with this commit included? And if
> not, try to enable CONFIG_MAILBOX.

Thank you!

That is indeed the cause. ab460a2e72da added a "depends on MAILBOX" to
CONFIG_RPMSG_QCOM_SMD, so CONFIG_RPMSG_QCOM_SMD becomes unset since
CONFIG_MAILBOX is not enabled in qcom_defconfig and is not otherwise
selected for the dragonboard.

Is there a config variable that should be selecting MAILBOX for a class
of systems that would include the APQ8074 Dragonboard? For my testing
I added the "select MAILBOX" to CONFIG_ARCH_MSM8974, but I do not know
what systems that includes, and whether it is appropriate to do the
select for all of them.

-Frank

>
> Regards,
> Bjorn
>
>> -Frank
>>
>>
>>>
>>> diff --git a/Documentation/devicetree/bindings/soc/qcom/qcom,smd.txt b/Documentation/devicetree/bindings/soc/qcom/qcom,smd.txt
>>> index ea1dc75ec9ea..234ae2256501 100644
>>> --- a/Documentation/devicetree/bindings/soc/qcom/qcom,smd.txt
>>> +++ b/Documentation/devicetree/bindings/soc/qcom/qcom,smd.txt
>>> @@ -22,9 +22,15 @@ The edge is described by the following properties:
>>> Definition: should specify the IRQ used by the remote processor to
>>> signal this processor about communication related updates
>>>
>>> -- qcom,ipc:
>>> +- mboxes:
>>> Usage: required
>>> Value type: <prop-encoded-array>
>>> + Definition: reference to the associated doorbell in APCS, as described
>>> + in mailbox/mailbox.txt
>>> +
>>> +- qcom,ipc:
>>> + Usage: required, unless mboxes is specified
>>> + Value type: <prop-encoded-array>
>>> Definition: three entries specifying the outgoing ipc bit used for
>>> signaling the remote processor:
>>> - phandle to a syscon node representing the apcs registers
>>> diff --git a/drivers/rpmsg/Kconfig b/drivers/rpmsg/Kconfig
>>> index 0fe6eac46512..2e4fb4ffd562 100644
>>> --- a/drivers/rpmsg/Kconfig
>>> +++ b/drivers/rpmsg/Kconfig
>>> @@ -39,6 +39,7 @@ config RPMSG_QCOM_GLINK_SMEM
>>>
>>> config RPMSG_QCOM_SMD
>>> tristate "Qualcomm Shared Memory Driver (SMD)"
>>> + depends on MAILBOX
>>> depends on QCOM_SMEM
>>> select RPMSG
>>> help
>>> diff --git a/drivers/rpmsg/qcom_smd.c b/drivers/rpmsg/qcom_smd.c
>>> index bc0b30657230..3ff271a44bef 100644
>>> --- a/drivers/rpmsg/qcom_smd.c
>>> +++ b/drivers/rpmsg/qcom_smd.c
>>> @@ -14,6 +14,7 @@
>>>
>>> #include <linux/interrupt.h>
>>> #include <linux/io.h>
>>> +#include <linux/mailbox_client.h>
>>> #include <linux/mfd/syscon.h>
>>> #include <linux/module.h>
>>> #include <linux/of_irq.h>
>>> @@ -107,6 +108,8 @@ static const struct {
>>> * @ipc_regmap: regmap handle holding the outgoing ipc register
>>> * @ipc_offset: offset within @ipc_regmap of the register for ipc
>>> * @ipc_bit: bit in the register at @ipc_offset of @ipc_regmap
>>> + * @mbox_client: mailbox client handle
>>> + * @mbox_chan: apcs ipc mailbox channel handle
>>> * @channels: list of all channels detected on this edge
>>> * @channels_lock: guard for modifications of @channels
>>> * @allocated: array of bitmaps representing already allocated channels
>>> @@ -129,6 +132,9 @@ struct qcom_smd_edge {
>>> int ipc_offset;
>>> int ipc_bit;
>>>
>>> + struct mbox_client mbox_client;
>>> + struct mbox_chan *mbox_chan;
>>> +
>>> struct list_head channels;
>>> spinlock_t channels_lock;
>>>
>>> @@ -366,7 +372,17 @@ static void qcom_smd_signal_channel(struct qcom_smd_channel *channel)
>>> {
>>> struct qcom_smd_edge *edge = channel->edge;
>>>
>>> - regmap_write(edge->ipc_regmap, edge->ipc_offset, BIT(edge->ipc_bit));
>>> + if (edge->mbox_chan) {
>>> + /*
>>> + * We can ignore a failing mbox_send_message() as the only
>>> + * possible cause is that the FIFO in the framework is full of
>>> + * other writes to the same bit.
>>> + */
>>> + mbox_send_message(edge->mbox_chan, NULL);
>>> + mbox_client_txdone(edge->mbox_chan, 0);
>>> + } else {
>>> + regmap_write(edge->ipc_regmap, edge->ipc_offset, BIT(edge->ipc_bit));
>>> + }
>>> }
>>>
>>> /*
>>> @@ -1326,27 +1342,37 @@ static int qcom_smd_parse_edge(struct device *dev,
>>> key = "qcom,remote-pid";
>>> of_property_read_u32(node, key, &edge->remote_pid);
>>>
>>> - syscon_np = of_parse_phandle(node, "qcom,ipc", 0);
>>> - if (!syscon_np) {
>>> - dev_err(dev, "no qcom,ipc node\n");
>>> - return -ENODEV;
>>> - }
>>> + edge->mbox_client.dev = dev;
>>> + edge->mbox_client.knows_txdone = true;
>>> + edge->mbox_chan = mbox_request_channel(&edge->mbox_client, 0);
>>> + if (IS_ERR(edge->mbox_chan)) {
>>> + if (PTR_ERR(edge->mbox_chan) != -ENODEV)
>>> + return PTR_ERR(edge->mbox_chan);
>>>
>>> - edge->ipc_regmap = syscon_node_to_regmap(syscon_np);
>>> - if (IS_ERR(edge->ipc_regmap))
>>> - return PTR_ERR(edge->ipc_regmap);
>>> + edge->mbox_chan = NULL;
>>>
>>> - key = "qcom,ipc";
>>> - ret = of_property_read_u32_index(node, key, 1, &edge->ipc_offset);
>>> - if (ret < 0) {
>>> - dev_err(dev, "no offset in %s\n", key);
>>> - return -EINVAL;
>>> - }
>>> + syscon_np = of_parse_phandle(node, "qcom,ipc", 0);
>>> + if (!syscon_np) {
>>> + dev_err(dev, "no qcom,ipc node\n");
>>> + return -ENODEV;
>>> + }
>>>
>>> - ret = of_property_read_u32_index(node, key, 2, &edge->ipc_bit);
>>> - if (ret < 0) {
>>> - dev_err(dev, "no bit in %s\n", key);
>>> - return -EINVAL;
>>> + edge->ipc_regmap = syscon_node_to_regmap(syscon_np);
>>> + if (IS_ERR(edge->ipc_regmap))
>>> + return PTR_ERR(edge->ipc_regmap);
>>> +
>>> + key = "qcom,ipc";
>>> + ret = of_property_read_u32_index(node, key, 1, &edge->ipc_offset);
>>> + if (ret < 0) {
>>> + dev_err(dev, "no offset in %s\n", key);
>>> + return -EINVAL;
>>> + }
>>> +
>>> + ret = of_property_read_u32_index(node, key, 2, &edge->ipc_bit);
>>> + if (ret < 0) {
>>> + dev_err(dev, "no bit in %s\n", key);
>>> + return -EINVAL;
>>> + }
>>> }
>>>
>>> ret = of_property_read_string(node, "label", &edge->name);
>>> @@ -1452,6 +1478,8 @@ struct qcom_smd_edge *qcom_smd_register_edge(struct device *parent,
>>> return edge;
>>>
>>> unregister_dev:
>>> + if (!IS_ERR_OR_NULL(edge->mbox_chan))
>>> + mbox_free_channel(edge->mbox_chan);
>>> put_device(&edge->dev);
>>> return ERR_PTR(ret);
>>> }
>>> @@ -1480,6 +1508,7 @@ int qcom_smd_unregister_edge(struct qcom_smd_edge *edge)
>>> if (ret)
>>> dev_warn(&edge->dev, "can't remove smd device: %d\n", ret);
>>>
>>> + mbox_free_channel(edge->mbox_chan);
>>> device_unregister(&edge->dev);
>>>
>>> return 0;
>>>
>>
>