RE: [EXT] Re: [PATCH v5 01/10] drm: bridge: cadence: convert mailbox functions to macro functions

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Hi Lucas,

Thanks your comments,

> -----Original Message-----
> From: Lucas Stach <l.stach@xxxxxxxxxxxxxx>
> Sent: 2022年12月9日 19:30
> To: Sandor Yu <sandor.yu@xxxxxxx>; andrzej.hajda@xxxxxxxxx;
> neil.armstrong@xxxxxxxxxx; robert.foss@xxxxxxxxxx;
> Laurent.pinchart@xxxxxxxxxxxxxxxx; jonas@xxxxxxxxx;
> jernej.skrabec@xxxxxxxxx; airlied@xxxxxxxxx; daniel@xxxxxxxx;
> robh+dt@xxxxxxxxxx; krzysztof.kozlowski+dt@xxxxxxxxxx;
> shawnguo@xxxxxxxxxx; s.hauer@xxxxxxxxxxxxxx; festevam@xxxxxxxxx;
> vkoul@xxxxxxxxxx; dri-devel@xxxxxxxxxxxxxxxxxxxxx;
> devicetree@xxxxxxxxxxxxxxx; linux-arm-kernel@xxxxxxxxxxxxxxxxxxx;
> linux-kernel@xxxxxxxxxxxxxxx; linux-phy@xxxxxxxxxxxxxxxxxxx
> Cc: Oliver Brown <oliver.brown@xxxxxxx>; dl-linux-imx
> <linux-imx@xxxxxxx>; kernel@xxxxxxxxxxxxxx
> Subject: [EXT] Re: [PATCH v5 01/10] drm: bridge: cadence: convert mailbox
> functions to macro functions
> 
> Caution: EXT Email
> 
> Hi Sandor,
> 
> Am Montag, dem 28.11.2022 um 15:36 +0800 schrieb Sandor Yu:
> > Mailbox access functions could be share to other mhdp driver and
> > HDP-TX HDMI/DP PHY drivers, move those functions to head file
> > include/drm/bridge/cdns-mhdp-mailbox.h and convert them to macro
> > functions.
> >
> 
> This does not look right. If those functions need to be called from other units
> and implemented in the header, they should simply be static inline functions
> rather than macros. Those macros obfuscate the code a lot.
> 
> However, I don't believe those should be called by other units directly. From
> what I can see this is mostly used by the PHY drivers, to interact with the
> mailbox and read/write PHY registers. However, there is no locking between
> the bridge and the core driver in any form, so they could corrupt the mailbox
> state. The PHY drivers have mailbox mutexes, but as far as I can see they
> aren't used and even if they were they would not guard against concurrent
> access to the mailbox between the bridge and the PHY driver.
Both PHY and bridge have its owner mutex to lock mailbox read/write.
In bridge driver, this mutex also lock for PHY API function access to avoid PHY and bridge driver race condition.

> 
> I think the right thing to do here would be to have a regmap implementation
> in the bridge driver, which uses the mailbox functions to implement the
> register access. Then this regmap could be passed down from the bridge
> driver to the PHY, which should simply be a child node of the bridge in DT.
> 
I'm not sure got your point " regmap implementation in the bridge driver".
Those mailbox functions also should be reused by mhdp8546.
Could you please explain detail or provide a sample?

Regards,
Sandor

> Regards,
> Lucas
> 
> > Signed-off-by: Sandor Yu <Sandor.yu@xxxxxxx>
> > ---
> >  .../drm/bridge/cadence/cdns-mhdp8546-core.c   | 197 +-------------
> >  .../drm/bridge/cadence/cdns-mhdp8546-core.h   |   1 -
> >  include/drm/bridge/cdns-mhdp-mailbox.h        | 240
> ++++++++++++++++++
> >  3 files changed, 242 insertions(+), 196 deletions(-)  create mode
> > 100644 include/drm/bridge/cdns-mhdp-mailbox.h
> >
> > diff --git a/drivers/gpu/drm/bridge/cadence/cdns-mhdp8546-core.c
> > b/drivers/gpu/drm/bridge/cadence/cdns-mhdp8546-core.c
> > index 31442a922502..b77b0ddcc9b3 100644
> > --- a/drivers/gpu/drm/bridge/cadence/cdns-mhdp8546-core.c
> > +++ b/drivers/gpu/drm/bridge/cadence/cdns-mhdp8546-core.c
> > @@ -36,6 +36,7 @@
> >  #include <linux/slab.h>
> >  #include <linux/wait.h>
> >
> > +#include <drm/bridge/cdns-mhdp-mailbox.h>
> >  #include <drm/display/drm_dp_helper.h>  #include
> > <drm/display/drm_hdcp_helper.h>  #include <drm/drm_atomic.h> @@
> > -55,200 +56,6 @@  #include "cdns-mhdp8546-hdcp.h"
> >  #include "cdns-mhdp8546-j721e.h"
> >
> > -static int cdns_mhdp_mailbox_read(struct cdns_mhdp_device *mhdp) -{
> > -     int ret, empty;
> > -
> > -     WARN_ON(!mutex_is_locked(&mhdp->mbox_mutex));
> > -
> > -     ret = readx_poll_timeout(readl, mhdp->regs +
> CDNS_MAILBOX_EMPTY,
> > -                              empty, !empty, MAILBOX_RETRY_US,
> > -                              MAILBOX_TIMEOUT_US);
> > -     if (ret < 0)
> > -             return ret;
> > -
> > -     return readl(mhdp->regs + CDNS_MAILBOX_RX_DATA) & 0xff;
> > -}
> > -
> > -static int cdns_mhdp_mailbox_write(struct cdns_mhdp_device *mhdp, u8
> > val) -{
> > -     int ret, full;
> > -
> > -     WARN_ON(!mutex_is_locked(&mhdp->mbox_mutex));
> > -
> > -     ret = readx_poll_timeout(readl, mhdp->regs +
> CDNS_MAILBOX_FULL,
> > -                              full, !full, MAILBOX_RETRY_US,
> > -                              MAILBOX_TIMEOUT_US);
> > -     if (ret < 0)
> > -             return ret;
> > -
> > -     writel(val, mhdp->regs + CDNS_MAILBOX_TX_DATA);
> > -
> > -     return 0;
> > -}
> > -
> > -static int cdns_mhdp_mailbox_recv_header(struct cdns_mhdp_device
> *mhdp,
> > -                                      u8 module_id, u8 opcode,
> > -                                      u16 req_size)
> > -{
> > -     u32 mbox_size, i;
> > -     u8 header[4];
> > -     int ret;
> > -
> > -     /* read the header of the message */
> > -     for (i = 0; i < sizeof(header); i++) {
> > -             ret = cdns_mhdp_mailbox_read(mhdp);
> > -             if (ret < 0)
> > -                     return ret;
> > -
> > -             header[i] = ret;
> > -     }
> > -
> > -     mbox_size = get_unaligned_be16(header + 2);
> > -
> > -     if (opcode != header[0] || module_id != header[1] ||
> > -         req_size != mbox_size) {
> > -             /*
> > -              * If the message in mailbox is not what we want, we need
> to
> > -              * clear the mailbox by reading its contents.
> > -              */
> > -             for (i = 0; i < mbox_size; i++)
> > -                     if (cdns_mhdp_mailbox_read(mhdp) < 0)
> > -                             break;
> > -
> > -             return -EINVAL;
> > -     }
> > -
> > -     return 0;
> > -}
> > -
> > -static int cdns_mhdp_mailbox_recv_data(struct cdns_mhdp_device
> *mhdp,
> > -                                    u8 *buff, u16 buff_size)
> > -{
> > -     u32 i;
> > -     int ret;
> > -
> > -     for (i = 0; i < buff_size; i++) {
> > -             ret = cdns_mhdp_mailbox_read(mhdp);
> > -             if (ret < 0)
> > -                     return ret;
> > -
> > -             buff[i] = ret;
> > -     }
> > -
> > -     return 0;
> > -}
> > -
> > -static int cdns_mhdp_mailbox_send(struct cdns_mhdp_device *mhdp, u8
> module_id,
> > -                               u8 opcode, u16 size, u8 *message)
> > -{
> > -     u8 header[4];
> > -     int ret, i;
> > -
> > -     header[0] = opcode;
> > -     header[1] = module_id;
> > -     put_unaligned_be16(size, header + 2);
> > -
> > -     for (i = 0; i < sizeof(header); i++) {
> > -             ret = cdns_mhdp_mailbox_write(mhdp, header[i]);
> > -             if (ret)
> > -                     return ret;
> > -     }
> > -
> > -     for (i = 0; i < size; i++) {
> > -             ret = cdns_mhdp_mailbox_write(mhdp, message[i]);
> > -             if (ret)
> > -                     return ret;
> > -     }
> > -
> > -     return 0;
> > -}
> > -
> > -static
> > -int cdns_mhdp_reg_read(struct cdns_mhdp_device *mhdp, u32 addr, u32
> > *value) -{
> > -     u8 msg[4], resp[8];
> > -     int ret;
> > -
> > -     put_unaligned_be32(addr, msg);
> > -
> > -     mutex_lock(&mhdp->mbox_mutex);
> > -
> > -     ret = cdns_mhdp_mailbox_send(mhdp, MB_MODULE_ID_GENERAL,
> > -                                  GENERAL_REGISTER_READ,
> > -                                  sizeof(msg), msg);
> > -     if (ret)
> > -             goto out;
> > -
> > -     ret = cdns_mhdp_mailbox_recv_header(mhdp,
> MB_MODULE_ID_GENERAL,
> > -
> GENERAL_REGISTER_READ,
> > -                                         sizeof(resp));
> > -     if (ret)
> > -             goto out;
> > -
> > -     ret = cdns_mhdp_mailbox_recv_data(mhdp, resp, sizeof(resp));
> > -     if (ret)
> > -             goto out;
> > -
> > -     /* Returned address value should be the same as requested */
> > -     if (memcmp(msg, resp, sizeof(msg))) {
> > -             ret = -EINVAL;
> > -             goto out;
> > -     }
> > -
> > -     *value = get_unaligned_be32(resp + 4);
> > -
> > -out:
> > -     mutex_unlock(&mhdp->mbox_mutex);
> > -     if (ret) {
> > -             dev_err(mhdp->dev, "Failed to read register\n");
> > -             *value = 0;
> > -     }
> > -
> > -     return ret;
> > -}
> > -
> > -static
> > -int cdns_mhdp_reg_write(struct cdns_mhdp_device *mhdp, u16 addr, u32
> > val) -{
> > -     u8 msg[6];
> > -     int ret;
> > -
> > -     put_unaligned_be16(addr, msg);
> > -     put_unaligned_be32(val, msg + 2);
> > -
> > -     mutex_lock(&mhdp->mbox_mutex);
> > -
> > -     ret = cdns_mhdp_mailbox_send(mhdp, MB_MODULE_ID_DP_TX,
> > -                                  DPTX_WRITE_REGISTER,
> sizeof(msg), msg);
> > -
> > -     mutex_unlock(&mhdp->mbox_mutex);
> > -
> > -     return ret;
> > -}
> > -
> > -static
> > -int cdns_mhdp_reg_write_bit(struct cdns_mhdp_device *mhdp, u16 addr,
> > -                         u8 start_bit, u8 bits_no, u32 val)
> > -{
> > -     u8 field[8];
> > -     int ret;
> > -
> > -     put_unaligned_be16(addr, field);
> > -     field[2] = start_bit;
> > -     field[3] = bits_no;
> > -     put_unaligned_be32(val, field + 4);
> > -
> > -     mutex_lock(&mhdp->mbox_mutex);
> > -
> > -     ret = cdns_mhdp_mailbox_send(mhdp, MB_MODULE_ID_DP_TX,
> > -                                  DPTX_WRITE_FIELD, sizeof(field),
> field);
> > -
> > -     mutex_unlock(&mhdp->mbox_mutex);
> > -
> > -     return ret;
> > -}
> > -
> >  static
> >  int cdns_mhdp_dpcd_read(struct cdns_mhdp_device *mhdp,
> >                       u32 addr, u8 *data, u16 len) @@ -2058,7
> +1865,7
> > @@ static void cdns_mhdp_atomic_disable(struct drm_bridge *bridge,
> >                                    struct drm_bridge_state
> > *bridge_state)  {
> >       struct cdns_mhdp_device *mhdp = bridge_to_mhdp(bridge);
> > -     u32 resp;
> > +     u32 resp = 0;
> >
> >       dev_dbg(mhdp->dev, "%s\n", __func__);
> >
> > diff --git a/drivers/gpu/drm/bridge/cadence/cdns-mhdp8546-core.h
> > b/drivers/gpu/drm/bridge/cadence/cdns-mhdp8546-core.h
> > index bedddd510d17..10c878bf0e63 100644
> > --- a/drivers/gpu/drm/bridge/cadence/cdns-mhdp8546-core.h
> > +++ b/drivers/gpu/drm/bridge/cadence/cdns-mhdp8546-core.h
> > @@ -212,7 +212,6 @@ struct phy;
> >  #define MB_MODULE_ID_HDCP_TX                 0x07
> >  #define MB_MODULE_ID_HDCP_RX                 0x08
> >  #define MB_MODULE_ID_HDCP_GENERAL            0x09
> > -#define MB_MODULE_ID_GENERAL                 0x0a
> >
> >  /* firmware and opcodes */
> >  #define FW_NAME
> "cadence/mhdp8546.bin"
> > diff --git a/include/drm/bridge/cdns-mhdp-mailbox.h
> > b/include/drm/bridge/cdns-mhdp-mailbox.h
> > new file mode 100644
> > index 000000000000..0249322a74b0
> > --- /dev/null
> > +++ b/include/drm/bridge/cdns-mhdp-mailbox.h
> > @@ -0,0 +1,240 @@
> > +/* SPDX-License-Identifier: GPL-2.0 */
> > +/*
> > + * Cadence MHDP Firmware Access API function by Malibox.
> > + *
> > + * Copyright (C) 2022 NXP Semiconductor, Inc.
> > + *
> > + */
> > +#ifndef CDNS_MHDP_MAILBOX_H
> > +#define CDNS_MHDP_MAILBOX_H
> > +
> > +#include <asm/unaligned.h>
> > +#include <linux/iopoll.h>
> > +
> > +/* mailbox regs offset */
> > +#define CDNS_MAILBOX_FULL                    0x00008
> > +#define CDNS_MAILBOX_EMPTY                   0x0000c
> > +#define CDNS_MAILBOX_TX_DATA         0x00010
> > +#define CDNS_MAILBOX_RX_DATA         0x00014
> > +
> > +#define MAILBOX_RETRY_US                     1000
> > +#define MAILBOX_TIMEOUT_US                   2000000
> > +
> > +/* Module ID Code */
> > +#define MB_MODULE_ID_GENERAL         0x0A
> > +#define MB_MODULE_ID_DP_TX                   0x01
> > +
> > +/* General Commands */
> > +#define GENERAL_REGISTER_WRITE               0x05
> > +#define GENERAL_REGISTER_READ                0x07
> > +
> > +/* DP TX Command */
> > +#define DPTX_WRITE_FIELD                     0x08
> > +
> > +/* MHDP Firmware access functions by Mailbox */ #define
> > +cdns_mhdp_mailbox_read(__mhdp) \ ({ \
> > +     int ret, empty, val; \
> > +\
> > +     WARN_ON(!mutex_is_locked(&(__mhdp)->mbox_mutex)); \ \
> > +     do {  \
> > +             ret = readx_poll_timeout(readl, (__mhdp)->regs +
> CDNS_MAILBOX_EMPTY,  \
> > +                                      empty, !empty,
> MAILBOX_RETRY_US,  \
> > +                                      MAILBOX_TIMEOUT_US);
> \
> > +             if (ret < 0)  \
> > +                     break;  \
> > +\
> > +             val = readl((__mhdp)->regs + CDNS_MAILBOX_RX_DATA)
> & 0xff; \
> > +     } while (0);  \
> > +\
> > +     (ret < 0) ? ret : val;  \
> > +})
> > +
> > +#define cdns_mhdp_mailbox_write(__mhdp, __val) \ ({ \
> > +     int ret, full;  \
> > +\
> > +     WARN_ON(!mutex_is_locked(&(__mhdp)->mbox_mutex)); \ \
> > +     do {  \
> > +             ret = readx_poll_timeout(readl, (__mhdp)->regs +
> CDNS_MAILBOX_FULL,  \
> > +                                      full, !full,
> MAILBOX_RETRY_US,  \
> > +                                      MAILBOX_TIMEOUT_US);
> \
> > +             if (ret < 0)  \
> > +                     break;  \
> > +\
> > +             writel((__val), (__mhdp)->regs +
> CDNS_MAILBOX_TX_DATA); \
> > +     } while (0);  \
> > +\
> > +     ret; \
> > +})
> > +
> > +#define  cdns_mhdp_mailbox_recv_header(__mhdp, __module_id,
> __opcode,
> > +__req_size) \ ({  \
> > +     u32 mbox_size, i;  \
> > +     u8 header[4];  \
> > +     int ret;  \
> > +\
> > +     do {  \
> > +             /* read the header of the message */ \
> > +             for (i = 0; i < sizeof(header); i++) {  \
> > +                     ret = cdns_mhdp_mailbox_read(__mhdp);  \
> > +                     if (ret < 0)  \
> > +                             break;  \ \
> > +                     header[i] = ret;  \
> > +             }  \
> > +\
> > +             mbox_size = get_unaligned_be16(header + 2);  \ \
> > +             if ((__opcode) != header[0] || (__module_id) != header[1]
> ||  \
> > +                 (__req_size) != mbox_size) {  \
> > +                     /* If the message in mailbox is not what we
> want, we need to
> > +                      * clear the mailbox by reading its contents. */
> \
> > +                     for (i = 0; i < mbox_size; i++)   \
> > +                             if (cdns_mhdp_mailbox_read(__mhdp)
> < 0)  \
> > +                                     break;  \ \
> > +                     ret = -EINVAL;  \
> > +             }  \
> > +\
> > +             ret = 0; \
> > +\
> > +     } while (0);  \
> > +\
> > +     ret;  \
> > +})
> > +
> > +#define cdns_mhdp_mailbox_recv_data(mhdp, buff, buff_size)  \ ({  \
> > +     u32 i;  \
> > +     int ret;  \
> > +\
> > +     do {  \
> > +             for (i = 0; i < buff_size; i++) {  \
> > +                     ret = cdns_mhdp_mailbox_read(mhdp);  \
> > +                     if (ret < 0)  \
> > +                             break;  \ \
> > +                     ((u8 *)buff)[i] = ret;  \
> > +             }  \
> > +\
> > +             ret = 0;  \
> > +\
> > +     } while (0);  \
> > +\
> > +     ret; \
> > +})
> > +
> > +#define cdns_mhdp_mailbox_send(mhdp, module_id, opcode, size,
> > +message)  \ ({  \
> > +     u8 header[4];  \
> > +     int ret, i;  \
> > +\
> > +     header[0] = opcode;  \
> > +     header[1] = module_id;  \
> > +     put_unaligned_be16(size, header + 2);  \ \
> > +     do {  \
> > +             for (i = 0; i < sizeof(header); i++) {  \
> > +                     ret = cdns_mhdp_mailbox_write(mhdp,
> header[i]);  \
> > +                     if (ret < 0)  \
> > +                             break;  \
> > +             }  \
> > +\
> > +             for (i = 0; i < size; i++) {  \
> > +                     ret = cdns_mhdp_mailbox_write(mhdp, ((u8
> *)message)[i]);  \
> > +                     if (ret < 0)  \
> > +                             break;;  \
> > +             }  \
> > +             ret = 0;  \
> > +     } while (0);  \
> > +\
> > +     ret;  \
> > +})
> > +
> > +#define cdns_mhdp_reg_read(mhdp, addr, value)  \ ({  \
> > +     u8 msg[4], resp[8];  \
> > +     int ret;  \
> > +\
> > +     put_unaligned_be32(addr, msg);  \ \
> > +     mutex_lock(&mhdp->mbox_mutex);  \ \
> > +     do {  \
> > +             ret = cdns_mhdp_mailbox_send(mhdp,
> MB_MODULE_ID_GENERAL,  \
> > +
> GENERAL_REGISTER_READ,  \
> > +                                          sizeof(msg), msg);  \
> > +             if (ret < 0)  \
> > +                     break;  \
> > +\
> > +             ret = cdns_mhdp_mailbox_recv_header(mhdp,
> MB_MODULE_ID_GENERAL,  \
> > +
> GENERAL_REGISTER_READ,  \
> > +                                                 sizeof(resp));
> \
> > +             if (ret < 0)  \
> > +                     break;  \
> > +\
> > +             ret = cdns_mhdp_mailbox_recv_data(mhdp, resp,
> sizeof(resp));  \
> > +             if (ret < 0)  \
> > +                     break;  \
> > +\
> > +             /* Returned address value should be the same as
> requested */  \
> > +             if (memcmp(msg, resp, sizeof(msg))) {  \
> > +                     ret = -EINVAL;  \
> > +                     break;  \
> > +             }  \
> > +\
> > +             *((u32 *)value) = get_unaligned_be32(resp + 4);  \
> > +                     ret = 0;  \
> > +     } while (0);  \
> > +\
> > +     mutex_unlock(&mhdp->mbox_mutex);  \
> > +     if (ret < 0) {  \
> > +             dev_err(mhdp->dev, "Failed to read register\n");  \
> > +             *((u32 *)value) = 0;  \
> > +     }  \
> > +\
> > +     ret;  \
> > +})
> > +
> > +#define cdns_mhdp_reg_write(mhdp, addr, val)  \ ({  \
> > +     u8 msg[8];  \
> > +     int ret;  \
> > +\
> > +     put_unaligned_be32(addr, msg);  \
> > +     put_unaligned_be32(val, msg + 4);  \ \
> > +     mutex_lock(&mhdp->mbox_mutex);  \ \
> > +     ret = cdns_mhdp_mailbox_send(mhdp, MB_MODULE_ID_GENERAL,
> \
> > +                                   GENERAL_REGISTER_WRITE,
> > +sizeof(msg), msg);  \ \
> > +     mutex_unlock(&mhdp->mbox_mutex);  \ \
> > +     ret;  \
> > +})
> > +
> > +#define cdns_mhdp_reg_write_bit(mhdp, addr, start_bit, bits_no, val)
> > +\ ({  \
> > +     u8 field[8];  \
> > +     int ret;  \
> > +\
> > +     put_unaligned_be16(addr, field);  \
> > +     field[2] = start_bit;  \
> > +     field[3] = bits_no;  \
> > +     put_unaligned_be32(val, field + 4);  \ \
> > +     mutex_lock(&mhdp->mbox_mutex);  \ \
> > +     ret = cdns_mhdp_mailbox_send(mhdp, MB_MODULE_ID_DP_TX, \
> > +                                  DPTX_WRITE_FIELD,
> sizeof(field),
> > +field);  \ \
> > +     mutex_unlock(&mhdp->mbox_mutex);  \ \
> > +     ret; \
> > +})
> > +
> > +#endif
> 





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