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

Frank Rowand
2018-08-31T03:58:03Z

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.

-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;
>