On Mon, Aug 22, 2016 at 3:25 PM, Noralf Trønnes <noralf@xxxxxxxxxxx> wrote:
> The SimpleDRM driver binds to simple-framebuffer devices and provides a
> DRM/KMS API. It provides only a single CRTC+encoder+connector combination
> plus one initial mode.
>
> Userspace can create dumb-buffers which can be blit into the real
> framebuffer similar to UDL. No access to the real framebuffer is allowed
> (compared to earlier version of this driver) to avoid security issues.
> Furthermore, this way we can support arbitrary modes as long as we have a
> conversion-helper.
>
> The driver was originally written by David Herrmann in 2014.
> My main contribution is to make use of drm_simple_kms_helper and
> rework the probe path to avoid use of the deprecated drm_platform_init()
> and drm_driver.{load,unload}().
> Additions have also been made for later changes to the Device Tree binding
> document, like support for clocks, regulators and having the node under
> /chosen. This code was lifted verbatim from simplefb.c.
>
> Cc: dh.herrmann@xxxxxxxxx
> Cc: libv@xxxxxxxxx
> Signed-off-by: Noralf Trønnes <noralf@xxxxxxxxxxx>
[...]
> + /* Count the number of regulator supplies */
> + for_each_property_of_node(np, prop) {
> + p = strstr(prop->name, SUPPLY_SUFFIX);
> + if (p && p != prop->name)
> + count++;
> + }
The regulator API should have functions for this rather than open coding it.
> +
> + if (!count)
> + return 0;
> +
> + sdrm->regulators = devm_kcalloc(&pdev->dev, count,
> + sizeof(struct regulator *),
> + GFP_KERNEL);
> + if (!sdrm->regulators)
> + return -ENOMEM;
> +
> + /* Get all the regulators */
> + for_each_property_of_node(np, prop) {
> + char name[32]; /* 32 is max size of property name */
> +
> + p = strstr(prop->name, SUPPLY_SUFFIX);
> + if (!p || p == prop->name)
> + continue;
This too.
> +
> + strlcpy(name, prop->name,
> + strlen(prop->name) - strlen(SUPPLY_SUFFIX) + 1);
> + regulator = devm_regulator_get_optional(&pdev->dev, name);
[...]
> + if (IS_ENABLED(CONFIG_OF_ADDRESS) && of_chosen) {
> + struct device_node *np;
> +
> + for_each_child_of_node(of_chosen, np) {
> + if (of_device_is_compatible(np, "simple-framebuffer"))
Rather than exporting of_chosen, this whole chunk can be replaced with
a of_find_compatible_node call. Yes, that would match if
simple-framebuffer exists somewhere else in the DT, but it is not the
kernel's job to do DT validation.
> + of_platform_device_create(np, NULL, NULL);
> + }
> + }
Rob
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